Background: Knowledge of the prevalence of chronic disease in the population is essential for health planners and providers.

Objectives:To present the results of a concentrated effort by the largest health maintenance organization in Israel (Clalit Health Services) in order to develop a comprehensive register of chronic diseases.

Methods: In 1998, all 2,704 primary care physicians in Israel’s largest health provider were requested to report on all patients with selected chronic diseases. In addition, all the filled prescriptions for medications relevant to the investigated diseases and all relevant hospitalization events were added to the database. Prevalence rates were calculated based on the reporting practices only (1,653 physicians responsible for a total of 1,409,725 adults).

Results: Hypertension (10.2/100), diabetes (6.1/100), hyperlipidemia (5.7/100), peptic ulcer (4.7/100) and ischemic heart disease (4.3/100) were the most prevalent. Females had significantly higher rates of hypothyroidism, psychoses, neu­roses and malignancies, and lower rates of ischemic heart disease, chronic obstructive pulmonary disease, heart failure and asthma. Arabs had higher rates of diabetes mellitus and lower rates of ischemic heart disease, hypertension and hyperlipidemia than Jews. About 20% of the adult population had one or more of the selected chronic diseases.

Conclusions: Differences in rates noted between physi­cians, not explainable by population characteristics, may reflect differences in the quality and delivery of health services. Rate differences between demographic subgroups call for further studies on the etiology, susceptibility and natural history of these diseases.