Some authors have stated that nail pitting never occurs in Reiter's syndrome. The case of a patient with incomplete Reiter's syndrome with nail pitting and HLA-A2, 28; B18, 27 is presented. Patients who have both psoriasis and Reiter's syndrome have demonstrated increased frequency of HLA-A2 and B27 and markedly decreased frequency of HLA loci associated with psoriasis. The particular finding of nail pitting is presented to illustrate that this change may occur in Reiter's syndrome and may reflect a predisposition to the development of psoriasis or psoriasiform lesions conferred by HLA-A2 with B27, as suggested by previously reported HLA typing studies.