The 26th International 500-Mile Sweepstakes Race was held at the Indianapolis Motor Speedway on Monday, May 30, 1938. For 1938, riding mechanics were made optional; however, no teams utilized them in the race.^[3] In addition, after seven years, the engine specifications were changed again. The 1930 "Junk" formula was eliminated. Normally aspirated engines were allowed 4.5 liters (down from 6.0 L), and superchargers would be permitted again, with a maximum displacement of 3.0 liters. Any fuel was allowed, which directly affected the race.

Ten-lap (25 mile) qualifying runs were utilized. This would be the final time this distance was used. Floyd Roberts won the pole position.

Row	Inside		Middle		Outside
1	23	Floyd Roberts	14	Russ Snowberger	8	Rex Mays
2	17	Tony Gulotta	3	Chet Miller	2	Ted Horn
3	1	Wilbur Shaw  W	34	Babe Stapp	27	Mauri Rose
4	16	Ronney Householder	26	Frank Brisko	5	Louis Meyer  W
5	22	Joel Thorne  R	54	Herb Ardinger	6	Jimmy Snyder
6	7	Bill Cummings  W	29	Frank Wearne	38	Chet Gardner
7	15	George Connor	47	Shorty Cantlon	35	Kelly Petillo  W
8	55	Al Miller	36	Al Putnam  R	21	Louis Tomei
9	45	Harry McQuinn	10	Tony Willman	37	Ira Hall
10	42	Emil Andres	12	George Bailey	58	Billy Devore
11	33	Henry Banks  R	9	Cliff Bergere	43	Duke Nalon  R

• First alternate: Charlie Crawford^[4]

• Frankie Beeder  R  (#45)
• Floyd Davis (#59)
• Fred Frame  W  (#32)
• Ralph Hepburn (#4)
• Deacon Litz (#52)
• Tazio Nuvolari  R  (#48, #54)
• Jack Petticord (#57)
• Johnny Sawyer (#53)
• Johnny Seymour (#56)
• Doc Williams (#46)
• Billy Winn (#18, #24)^[5]

Floyd Roberts started in the pole position.

By 200 miles completed, Jimmy Snyder led a trio of alcohol-powered cars, followed by Roberts and Wilbur Shaw in cars running gasoline. When the alcohol cars pitted to re-fuel, Roberts took the lead for the first time. At 300 miles, Roberts made his one and only pit stop for fuel and a single tire change, and gave up the lead to Snyder. At 375 miles, Snyder made his 3rd stop for more methanol, and Roberts re-took a lead he would not relinquish to the checkered. ^[6]

Roberts led 92 laps, posted an average speed of 117.200 miles per hour, and won $32,075.^[7] Roberts' car was owned by Lou Moore, who was also the chief mechanic.

For this race, only the front and back straightaways were still surfaced with the original bricks installed in 1909. All 4 turns were paved with asphalt prior to this race. ^[8]

The race was run under heavily overcast skies, with rain threatening the entire day. But it did not rain until the race was completed. ^[9]

The race was marred by the death of 33-year-old spectator Everett Spence. On lap 45 the number 42 car driven by Emil Andres hit the wall in turn two, then flipped over several times, causing its right front wheel to fly off. The wheel traveled 100 feet (30 m) through the air and hit Spence, who was pronounced dead upon arriving at the hospital. Andres suffered a concussion, broken nose, and chest injuries.^[10]

Finish	Start	No	Name	Entrant	Chassis	Engine	Qual	Rank	Laps	Status
1	1	23	Floyd Roberts	Lou Moore	Wetteroth	Miller	125.681	2	200	117.200 mph
2	7	1	Wilbur Shaw  W	W. Wilbur Shaw	Shaw	Offenhauser	120.987	13	200	+3:55.27
3	5	3	Chet Miller	Boyle Racing Headquarters	Summers	Offenhauser	121.898	9	200	+5:21.11
4	6	2	Ted Horn	Harry Hartz	Wetteroth	Miller	121.327	12	200	+11:43.99
5	18	38	Chet Gardner	Joe Lencki	Rigling	Offenhauser	120.435	17	200	+16:19.08
6	14	54	Herb Ardinger (Russ Snowberger Laps 84–92) (Cliff Bergere Laps 122–199)	Lewis W. Welch	Miller-Ford	Offenhauser	119.022	24	199	Flagged
7	25	45	Harry McQuinn (Tony Willman Laps 87–169)	Carl Marchese	Marchese	Miller	119.492	21	197	Flagged
8	30	58	Billy Devore	Joel Thorne, Inc.	Stevens	Offenhauser	116.339	30	185	Flagged
9	13	22	Joel Thorne  R	Joel Thorne, Inc.	Shaw	Offenhauser	119.155	23	185	Flagged
10	17	29	Frank Wearne	Paul Weirick	Adams	Offenhauser	121.405	11	181	Flagged
11	33	43	Duke Nalon  R	Henry Kohlert	Fengler	Miller	113.828	33	178	Flagged
12	29	12	George Bailey	Leon Duray	Weil	Duray	116.393	29	166	Clutch
13	9	27	Mauri Rose	Boyle Racing Headquarters	Maserati	Maserati	119.796	20	165	Supercharger
14	10	16	Ronney Householder (Billy Winn Laps 139–154)	Joel Thorne, Inc.	Adams	Sparks	125.769	1	154	Supercharger
15	15	6	Jimmy Snyder	Joel Thorne, Inc.	Adams	Sparks	123.506	4	150	Supercharger
16	12	5	Louis Meyer  W	Bowes Racing, Inc.	Stevens	Winfield	120.525	16	149	Oil Pump
17	4	17	Tony Gulotta	Tony Gulotta	Stevens	Offenhauser	122.499	6	130	Rod
18	22	55	Al Miller	Jack Holly	Miller	Miller	119.420	22	125	Clutch
19	19	15	George Connor	Joseph Marks	Adams	Miller	120.326	18	119	Engine
20	32	9	Cliff Bergere	George H. Lyons	Stevens	Miller	114.464	32	111	Piston
21	31	33	Henry Banks  R	Louis Kimmel	Miller	Voelker	116.279	31	109	Rod bearing
22	21	35	Kelly Petillo  W	Kelly Petillo	Wetteroth	Offenhauser	119.827	19	100	Camshaft
23	24	21	Louis Tomei	H. E. Winn	Miller	Miller	121.599	10	88	Rod
24	16	7	Bill Cummings  W	Boyle Racing Headquarters	Miller	Miller	122.393	7	72	Radiator
25	2	14	Russ Snowberger	Russ Snowberger	Snowberger	Miller	124.027	3	56	Rod
26	8	34	Babe Stapp	Bill White Race Cars, Inc.	Weil	Miller	120.595	15	54	Valve
27	26	10	Tony Willman	Murrell Belanger	Stevens	Miller	118.458	25	47	Valve
28	3	8	Rex Mays	Bill White Race Cars, Inc.	Alfa Romeo-Weil	Alfa Romeo	122.845	5	45	Supercharger
29	28	42	Emil Andres	Elgin Piston Pin Company	Adams	Brisko	117.126	27	45	Crash T2
30	27	37	Ira Hall	Nowiak & Magnee	Nowiak	Studebaker	118.255	26	44	Crash T3
31	11	26	Frank Brisko	Frank Brisko	Stevens	Brisko	121.921	8	39	Oil line
32	23	36	Al Putnam  R	Arthur M. Sims	Stevens	Miller	116.791	28	15	Crankshaft
33	20	47	Shorty Cantlon	Thomas O'Brien	Stevens	Miller	120.906	14	13	Supercharger
[11][12]

Note: Relief drivers in parentheses^[13]

 W  Former Indianapolis 500 winner

 R  Indianapolis 500 Rookie

• After the 5th-place car finished 200 laps, rain brought out the yellow flag. Moments later, rain started to fall harder, and the red flag was put out ending the race. All cars still on the track were flagged off.^[14][15]

• 1938 AAA Championship Car season