Newborns in Finland have been vaccinated withBacillus Calmette-Guérin(BCG) since the 1950s. Until the end of 1970 the vaccine was made from BCG strain Gothenburg by the Swedish BCG laboratory in Gothenburg and from 1971 on from the same strain in Copenhagen, Denmark. It was replaced by the Glaxo vaccine in 1978. Complications caused by BCG vaccination have been under follow-up, and the data have been collected from nationwide registers. In this study we analyzed the incidence rates of BCG osteitis between the years 1960 and 1988. From 1960 to 1970 the incidence rate was from 2.7 to 13.0/100 000 BCG-vaccinated infants (mean, 7.3; median, 6.9). The incidence increased during the years 1971 to 1978 when it varied between 15.3 and 72.9/100 000 BCG-vaccinated infants (mean, 36.9; median, 30.4). Since 1978 the incidence has varied between 1.7 and 10.1/100 000 BCG-vaccinated infants (mean, 6.4; median, 7.2). In Britain no reports of BCG osteitis have been published despite the use of the same Glaxo vaccine. Our results indicate that the incidence of BCG osteitis in a given population depends on the BCG vaccine used. The follow-up of BCG complications is an essential part of BCG vaccination program.