Lettuce is a vegetable that is always consumed raw. The number and types of microorganisms that may be found on the lettuce leaves depend on growing, harvesting, and particularly on handling practices, like proper washing and preparing lettuce before eating. The aim of this study was to investigate the effect that washing under running water has on the microbiological status of lettuce leaves purchased from the local market place in Banja Luka. Smears were taken from the obverse and reverse sides of lettuce leaves, and the total count of aerobic mesophilic bacteria, yeasts and molds was determined as well as the presence of sulphite-reducing clostridia, the coagulase positive staphylococci, Salmonella species, and Escherichia coli. The analysis showed that the washing reduced the total count of aerobic mesophilic bacteria by approximately 10 times, and the total count of yeasts and molds by approximately 8 times. Of the lettuce samples examined, 66,67% contained sulphite-reducing clostridia and 13,33% Salmonella species, before the washing. The number of samples with sulphite-reducing clostridia was reduced by five times after the washing, but the number of samples contaminated with Salmonella species remained the same.