Urine Processor Assembly 
Ulster Protestant Action 
UltraSPARC Port Architecture 
unitary-pole approximation 
Usability Professionals' Association 
Air Foyle 
Ultra Port Architecture 
Ultrafine-Particle Analyzer 
ultraperforming algorithm 
Underprivileged Area 
Uniform Parentage Act 
United Printers Association 
United Progressive Alliance 
Univeristy Property Administration 
Universal Port Architecture 
Universities Personnel Association 
University of Pennsylvania 
University Photographers Association 
University Press of America, Inc. 
Unreimbursed Public Assistance 
Uranium Palladium Aluminide 
Uranium Producers of America 
Urban Programme Authority 
Urban Promise Academy 
Urban Protection Agency 
urinary plasminogen activator 
urinary-type plasminogen activator 
urinase type plasminogen activators 
urokinase PA 
Urokinase plasminogen activator