In 1973 an increase in the number of osteitis caused by BCG vaccination in the neonatal period was observed in Sweden. A high incidence of this complication, i.e. 1 case per 3000 vaccinated newborn children continued until this vaccination was interrupted in 1975. In the years 1972 to 1980 a total of 90 cases were reported to the Adverse Drug Reaction Committee. Earlier retrospective studies had disclosed 36 cases born between 1949-1968 and an active search for unreported cases in the 1970s revealed an additional 26 cases. Of the total of 152 known cases in Sweden, 82 were boys and 70 girls. The mean incubation period was 14 months for boys and 23 for girls. Extremely long incubation periods were seen, i.e. 6 years in two children and 12 years in one. Eleven children had multiple osteitis lesions. The epiphyses of the long bones of the extremities were the most frequent sites of the affection (109 lesions). Only in 6 patients the spine, which is the common site of osteitis caused by tuberculosis, was affected. Relapses occurred in two patients.