®rst documented outbreak of salmonellosis associated with the consumption of peanut butter was reported. This study was undertaken to determine survival characteristics of high (5Á68 log 10 cfu g À1 ) and low (1Á51 log 10 cfu g À1 ) inocula of a ®ve-serotype mixture of Salmonella in ®ve commercial peanut butters and two commercial peanut butter spreads. Populations in samples inoculated with 5Á68 log 10 cfu g À1 and stored for 24 weeks at 21 or 5 C decreased 4Á14±4Á50 log 10 cfu g À1 and 2Á86±4Á28 log 10 cfu g À1 , respectively, depending on the formulation. The order of retention of viability was: peanut butter spreads > traditional (regular) and reduced sugar, low-sodium peanut butters > natural peanut butter. Differences in rates of inactivation are attributed to variation in product composition as well as size and stability of water droplets in the colloidal matrix, which may in¯uence nutrient availability. With the exception of natural peanut butter, products initially inoculated with 1Á51 log 10 cfu of Salmonella g À1 (32 cfu g À1 ) were positive for the pathogen after storage for 24 weeks at 5 C. At 21 C, however, with the exception of one peanut butter spread, all products were negative for Salmonella after storage for 24 weeks. Post-process contamination of peanut butters and spreads with Salmonella may to result in survival in these products for the duration of their shelf life at 5 C and possibly 21 C, depending on the formulation.