Background: The ABO blood group antigens play a role in thepathophysiology of some diseases and several researches haveinvestigated this relationship in the field of dermatology. In thepresent study, an attempt was made to find the distribution ofblood types in patients with pemphigus vulgaris and chronicplaque type psoriasis.Method: Fifty patients with chronic plaque type psoriasis, 50patients with pemphigus vulgaris and 100 healthy persons ascontrol group, were selected as the study population. ABO bloodgrouping was determined by the cell type tube test method, usingstandard commercial anti/A, anti/B and 5% suspension of redblood cells. Chi square test was used to compare the frequencyof ABO blood groups in patients and control groups.Result: Among the 50 patients with psoriasis, 21 (42%) hadblood group O, 15 (30%) blood group A, 10 (20%) blood groupB and 8 (4%) had blood group AB. Among the 50 patients in thepemphigus group, 22 (44%) had blood group O, 19 (38%) bloodgroup A, 8 (16%) blood group B and 1 (2%) had blood groupAB. The distribution of blood groups in patients with these twodiseases was not significantly different from the control group.Conclusion: Despite some researches, which found associationsbetween blood group antigens and psoriasis or pemphigus, thisstudy did not find any such relationship.