The microbiological effects of 0.5% poly- and pyrophosphates were studied in laboratory media and in fresh or cooked, vacuum packaged bratwurst-type sausage held under refrigeration (5(DEGREES)C) and subsequent elevated temperatures (24-25(DEGREES)C). Tetrasodium pyrophosphate (TSPP), heated or unheated, was most inhibitory to selected bacteria in laboratory media, while sodium tripolyphosphate (STPP) and sodium polyphosphate glassy (SPG) lost their antimicrobial properties upon heating and sodium acid pyrophosphate (SAPP) was ineffective. Although phosphate addition consistently resulted in lower bacterial numbers, none of the phosphates exhibited significant (P 0.05) antibacterial effects in frozen beef patties held 90 days at -20(DEGREES)C, but inhibited bacterial growth at 24-25(DEGREES)C and significantly (P < 0.05) increased pH, orthophosphate content, palatability and overall acceptability scores of beef patties.