alpha 1B-glycoprotein (A1BG) polymorphism was examined in a Danish family material (no. 604-1505) with particular regard to markers on chromosome 19. For A1BG-LU we found a lod score z = 3.06 at theta = 0.05 in males, and z = 1.42 at theta = 0.10 in females, which assigns A1BG to chromosome 19. Close linkage to C3, SE, PEPD, APOC2, D19S7, D19S8 and D19S9 was excluded. The most likely order would appear to be C3-SE-LU-A1BG.