In the Netherlands gastroenteritis belongs to the ten diseases with the highest incidence rates. A sentinel study on the incidence of gastrointestinal complaints and the occurrence of the investigated pathogens (Campylobacter, Salmonella and Shigella) was carried out in about 40 general practices in 1992 and 1993. The sentinel stations were as representative as possible of the Dutch population. The study was undertaken by the National Institute of Public Health and Environmental Protection (RIVM) and the Netherlands Institute of Primary Health Care (NIVEL) in cooperation with the general practitioners who participated in the Dutch Sentinel Practice Network and 24 laboratories. Age and sex of patients who met the case definition were reported to the NIVEL. These patients were asked by their GP to provide a stool sample and to complete a questionnaire. The number of patients that were either reported to the NIVEL or have been given a questionnaire by their GP was estimated at about 2370. A completed questionnaire was received from 58.9% (1400/2370) of these patients. Eighty percent (1400/1744) of the cases completed the questionnaire they received. Results of microbiological analysis were obtained for 89.1% (1248/1400) of patients who completed the questionnaire. The crude incidence rate of acute gastrointestinal complaints was 55.3 per 10,000 person years, after correction for non response it was 89.9 per 10,000 person years. The incidence was lower in 1993 than in 1992. Between men and women no differences have been found. The highest incidences have been found in the agegroups under five. The incidence rate for Campylobacter was 6.9 per 10,000 person years (182 samples positive), for Salmonella 2.2 (55 samples positive) and for Shigella 0.4 per 10,000 person years (10 samples positive). After correction for non response these incidences were 11.7 and 3.5 and 0.6 per 10,000 person years. The Salmonella incidence rate was higher in 1993 than in 1992 and higher in men than in women. The highest incidence rates for Campylobacter and Salmonella were found in the agegroups under five. The (late) summer months as expected, showed the highest incidence rates. Incidence rates for gastroenteritis as well as for microorganisms were lower than incidences found in other sentinels. To follow trends in incidence rates and microorganisms it is necessary to undertake sentinels repeatedly with the same methodology and population. However results cannot be generalised to the general population and consequently it remains necessary to carry out a population cohort study every 5 to 10 years.