MLD may refer to:

• Manual lymphatic drainage
• Metachromatic leukodystrophy, a rare neurometabolic genetic condition

• Masking Level Difference, see Auditory masking
• Mean log deviation in statistics and econometrics
• Mixed layer depth in hydrography
• Multicast Listener Discovery, in computer networking
• Million liter per day, in environmental engineering

• ICAO airline designator of Air Moldova
• Maldives, ITU country code
• Maniac Latin Disciples, a street gang
• Marine Luchtvaart Dienst, the Dutch Naval Aviation Service
• Mutually locally derivable, a mathematical property of aperiodic tile sets
• EU Money Laundering Directive
• Miluo East railway station, China Railway pinyin code MLD
• Moderate Learning Difficulties, a recognised form of Special Educational Needs (SEN)
• Monolingual learner's dictionary, type of dictionary designed to meet the reference needs of people learning a foreign language.
• Moreland railway station, Melbourne