Portland Trail Blazers, a professional basketball team

in Biochemistry:

Phosphotyrosine-binding Domain (usually denoted as PTB-domain)

Workers Party of Belgium (Parti du Travail de Belgique)

Power Tab file extension (.ptb)

Brazilian Labour Party

The powers that be

Polypyrimidine-tract binding protein

Party of Labour of Burkina (Parti du Travail de Burkina)

Physikalisch-Technische Bundesanstalt, the national standards laboratory of Germany

Placer Theatre Ballet the ballet company for Placer County, California USA.

PTB (band), a Melbourne, Australia based melodic metal band

Ptahhotep's Team Balancer a Counter-Strike plugin