The 25th Biathlon World Championships were held in 1990 for the third time in Minsk, Belarus, at that time part of the Soviet Union, in Oslo, Norway and in Kontiolahti, Finland. Due to unconducive weather conditions during the season it was only possible to hold the individual competitions in Minsk. The sprints, the women's relay and team events were held in Oslo and the men's relay was finally held in Kontiolahti.
References
Biathlon World Championships 1990 Wikipedia(Text) CC BY-SA