The longest English acronym listed in the 1965 edition of the
Acronyms, Initialisms, and Abbreviations Dictionary is a U.S. Navy acronym:
ADCOMSUBORDCOMPHIBSPAC
AD - Administrative
COM - Command
SUBORD - Subordinate
COM - Command
PHIBS - Amphibious Forces
PAC - Pacific Fleet
But wait - the Russians couldn't stand to be bested in the bad old days of the 'Evil Empire'; the world's longest acronym according to the
Guinness Book of World Records is:
NIIOMTPLABOPARMBETZHELBETRABSBOMONIMONKONOTDTEKHST ROMONT (56 letters, 54 in Cyrillic).
Found in the
Concise Dictionary of Soviet Terminology, it means: "The laboratory for shuttering, reinforcement, concrete and ferroconcrete operations for composite-monolithic and monolithic constructions of the Department of the Technology of Building-assembly operations of the Scientific Research Institute of the Organization for building mechanization and technical aid of the Academy of Building and Architecture of the USSR."
Source:
http://members.aol.com/gulfhigh2/words1.html