A study was undertaken to determine the etiological agents responsible for epidemics in a small and relatively isolated Arctic community.Three serological surveys were carried out over a four-year period employing complement fixation tests. Clinical information from the resident nurse was also available.The results indicated that of the two clinical epidemics of "influenza" which occurred during the period of study one was due to influenza virus type A; the other was unidentified. However, influenza virus type B affected approximately 30% of the population at some time during a two-year period without being clinically recognized. An epidemic affecting mainly children, which was clinically considered to be whooping cough, was probably caused by an adenovirus. A mumps epidemic with a high attack rate for all age groups which had occurred a few months prior to the first survey was confirmed. Sendai virus and psittacosis virus are probably endemic in this community.