Seven pedigrees with bipolar affective disorder (BPD2) have been found to show a pattern consistent with autosomal dominant genetic inheritance in linkage with, but distal to, HLA on the short arm of chromosome 6. Segregation analysis of subjects by narrow criteria yielded lod score 8.02 at theta = 0.15. Four pedigrees of three to five generations contributed most to the total score. Note is made of high concordance of marker HLA haplotype in affected sibs.