a b s t r a c tThis study evaluated the microbiological quality of 180 lettuce samples (Lactuca sativa) of the iceberg variety from different cropping systems and examined the efficacy of two sanitizers in reducing the bacterial counts. The results showed high contamination by mesophilic aerobic bacteria in traditionally grown and organically grown samples, which also possessed thermotolerant coliforms above the recommended levels in 66% and 80% of samples, respectively. Salmonella sp. was not detected in any of the analyzed samples. Traditionally grown and organically grown samples also exhibited a high frequency of intestinal parasites, including the pathogenic Taenia sp. and the Entamoeba histolytica species. In contrast, only 20% of hydroponically grown lettuce samples were contaminated with parasites. Sodium hypochlorite and acetic acid at concentrations of 100 mg L À1 and 1%, respectively, were effective in reducing bacterial counts, even in samples with high levels of contamination.