The diphtheria epidemic that began in Russia in 1990 reached Kazakhstan in 1992 when 45 case-patients (a 50% increase over 1991) were reported. In 1993, 82 case-patients were reported, and 489 were reported in 1994. The epidemic peaked in 1995 when 1105 case-patients were reported (incidence rate=6.7/100,000 population). In 1996, after public health practice modifications and several mass vaccinations, 455 case-patients were reported. From 1990 to 1996, children