- Background. Two ethnic populations (westernized Jews and Bedouins in transition from seminomadic to sedentary life conditions) living in Southern Israel and receiving inpatient services in the only medical facility of the region. Objective. To determine whether the incidence and severity of Streptococcus pyogenes infections among Jewish and Bedouin children have changed over the years. Study design. Retrospective (1980 to 1994), population-based. Medical charts of children younger than 15 years of age hospitalized with S. pyogenes bacteremia and/or severe invasive infection were reviewed. Incidence rates of bacteremia among Jewish and Bedouin children were calculated separately. Results. The incidence of S. pyogenes bacteremia was 2.82/100 000 between 1980 and 1984, was 2.58/100 000 between 1985 and 1989 and rose significantly during 1990 through 1994 to 4.82/100 000 (P < 0.01). The observed increment was the result of a significant increase among the Jews, whereas the incidence among the Bedouin population remained relatively stable. Streptococcal toxic shock syndrome was diagnosed in three Jewish patients between 1992 and 1994. No predominance of any particular streptococcal M-type was observed. Conclusions. The incidence of pediatric S. pyogenes bacteremia has increased in Southern Israel in recent years. This increase has occurred among the Jewish population, among which the first cases of streptococcal toxic shock syndrome have recently occurred. The increased incidence observed is not the result of dissemination of a single virulent streptococcal clone.