Although diphtheria was controlled for approximately 30 years after the institution of childhood vaccination with diphtheria toxoid in the late 1950s, epidemic diphtheria has reemerged in the New Independent States (NIS) of the former Soviet Union (1,2) (Figures 1 and 2). The epidemic began in 1990 in the Russian Federation and spread to Ukraine in 1991 and, during 1993-1994, to 12 of the 13 remaining NIS. In most affected countries, the incidence rate of reported diphtheria has increased twofold to 10-fold each year. This report summarizes data provided to the World Health Organization (WHO) about diphtheria in the NIS during 1989-1994.*