An epidemic of group B meningococcal disease on the Faroe Islands is described. A peak annual incidence of 95 cases/100,000 was reached in 1981. The time at which the epidemic commenced cannot be determined due to inadequate diagnostic facilities, but was presumably around the end of the 1970s. The incidence fell to 29 cases/100,000 in 1985, which indicates that the Faroe Islands are still a high incidence area. A total of 203 cases of meningococcal disease were recorded during the period 1978-1985 with 11 deaths (lethality rate 5.4%). After rifampicin was introduced in 1981 as prophylactic treatment against secondary cases, 1,892 persons were treated with this agent and none of these appeared in the study population. Before rifampicin prophylaxis was introduced, the number of cases were distributed with an evenly increasing incidence in the capital and in the provinces. Following the introduction of rifampicin as prophylactic agent, a fall in the incidence in both areas was observed. This fall was more pronounced in the capital, where the number of prescribed prophylactic doses per case of meningococcal disease was higher than in the province.