Two different population groups reside in the Negev region of southern Israel and have equal, and free from financial barrier, access to tertiary care at a single regional hospital. The Jewish population has a largely urban and industrialized lifestyle, while the Moslem Bedouins are in transition from their traditional nomadic life to settlement. To examine the differences in morbidity patterns reflected in hospitalizations, the computerized hospitalization records of children <15 years of age, for 1989-1991 were used (n=15,947). Rates of hospitalizations for infectious diseases were significantly higher for Bedouins in comparison to Jews (250 and 121/10,000 child years, respectively, odds ratio (OR): 2.1, 95% confidence interval (CI): 2.0-2.2, p < 0.001). Rates of hospitalization per 10,000 child years in Bedouins and Jews for diarrhea were 114 and 32 (OR: 3.7, 95% CI: 3.3-4.0, p < 0.001), respectively, and for pneumonia 55 and 19 (OR: 2.9, 95% CI: 2.6-3.3, p < 0.001), respectively. In infants the differences were even more pronounced, especially for diarrheal diseases. In Bedouin children infectious diseases were associated with longer hospital stay, more pediatric Intensive Care hospitalizations (OR: 2.7, 95% CI: 1.7-4.5,p < 0.001), and higher in-hospital mortality (OR: 5.7, 95% CI: 2.8-12.2, p < 0.001). Thus, Bedouin children are at higher risks of hospitalizations for infectious diseases in early childhood, as compared to Jewish children. This may reflect the differences in lifestyle, environmental and social conditions of the two populations.