The potential for microbial transfer in self-service laundry washing machines was investigated by obtaining swab samples from the interior surfaces of commercial machines and wash water samples before and after disinfectant treatment. Three disinfectants (chlorine, a quaternary ammonium product, and a phenolic disinfectant) were used. Four self-service laundry facilities were sampled, with 10 replications of the procedure for each treatment at each location. Although washers were set on a warmwater setting, the wash water temperatures ranged from 24 to 51°C. The quaternary ammonium product seemed most effective, averaging a 97% microbial kill; chlorine was the second most effective, with a 58% kill, and the phenolic disinfectant was least effective, with only a 25% kill. The efficacies of the chlorine and phenolic disinfectants were reduced at low water temperatures commonly experienced in self-service laundries. Interfamily cross-contamination in self-service facilities is a potential public health problem, which is aggravated by environmental conditions, such as water temperature and the practices of the previous users of the equipment. Procedural changes in laundering are recommended, including the use of a disinfectant to maintain adequate levels of sanitation.