A case of a 38-year old man with a common variable immunodeficiency syndrom
e (CVID) is demonstrated who suffered at the same time from a histologicall
y proven inclusion body myositis (IBM). The myositis did not resolve after
institution of regular intravenous IgG infusions. This case demonstrates a
very long lasting benign course of IBM. The occurrence with CVID may be a c
linical hint for a viral pathogenesis of IBM. So far only two similar cases
are reported in the literature.