Studies of the underlying components of affective disorders are particularly difficult because of the confounding effects of both genetic and environmental factors. Linkage analysis is a useful tool in delineating the etiology of affective disorders, as it is unlikely that linkage between behavioral traits and blood group polymorphisms could result from environmental effects. The present study used the robust Haseman and Elston sibpair method to analyze linkage between 24 genetic markers and affective disorder in 34 nuclear families from 25 pedigrees (195 people). The probands were ascertained as part of the ongoing NIMH Collaborative Depression Study. Indications of linkage between familial pure depressive disease and MNS and depression spectrum disease and ORM were found, as had been previously suggested. There was also suggestive evidence for linkage between the latter and GC. Results are discussed in terms of methodological differences with previous studies.