Beef tissue surfaces (lean and fat) were artificially contaminated with Salmonella typhimurium and then sanitized with 2% acetic acid. The reduction in bacterial population by the acid treatment was consistently proportional to the initial inoculum level for both tissue types. Increasing the amount of organic material in the inoculating menstra reduced the bactericidal effects of acetic acid on Salmonella typhimurium on fat tissue, although there was no change in effectiveness on lean tissue. Acid treatment sublethally injured about 65% of the population on both lean and fat tissue, and the residual effects of the acid resulted in a 1 log cycle reduction in bacterial population on fat tissue over 4 hr.