During a period of 2 years (2000 and 2001) 996 Shigella flexneri strains from sporadic cases in Israel were sent to the National Shigella Reference Centre (NSRC) by hospital and outpatient clinics. The most common serotypes were 2a, 6 and 1b, accounting for 88·4% of all isolates. They were investigated according to the monthly distribution of the strains, and the age and sex of the patients. The severity of the disease was assessed by a hospital/outpatient distribution (H/Od) of the isolates, based on the location of the sending laboratory. The most affected age groups were 0–11 months and 1–4 years, and the prevalent serotype was 2a, while serotype 6 was dominant in the 5–14 years age group. More cases were registered during the hot season, and there were some serotype-related variations. Overall, 62·1% of the samples were from male patients. Serotype 1b was dominant in the male/female ratio, although it was third in general prevalence. According to the H/Od serotype 2a was more common in hospitalized males and serotype 6 in outpatients, both male and female. These variations, as well as changes in serotype prevalence in the past, underscore the importance of serotype monitoring as part of the public health strategies for reducing the burden of Shigella flexneri infections.