To study the calcium sensitivity of sheep hair follicle transglutaminase, which was reportedly calcium-independent [H. W. Harding and G.E. Rogers, Biochemistry, 11, 2858-2863 (1972)], the enzyme was purified from a homogenate of merino sheep hair follicles and its calcium dependence was examined. As a result of purification, two types of transglutaminases (DEAE-unabsorbed and absorbed transglutaminase, DU-TG and DA-TG, respectively) were obtained. The molecular mass of DU-TG was 77 and 82 kDa by SDS-PAGE and gel filtration, respectively, while that of DA-TG was 40 and 80 kDa. Each enzyme was obviously calcium dependent and contained (a) cysteine residue(s) in the active site, like other known mammalian transglutaminases. Maximum activation of DU-TG and DA-TG was observed at 1 and 0.1 mM CaCl2, respectively.