Abstract: There is some data in the literature on the association of HLA-B5 and some manifestations of Behçet’s disease (BD), especially ocular lesions. We studied 433 patients to see if there was any relationship between B51 and the manifestations of the disease. Clinical manifestations of BD were compared in patients having HLA-B51 (155 patients) and those lacking HLA-B51 (278 patients). Oral aphthosis, genital aphthosis, skin manifestations, joint manifestations, gastrointestinal manifestations, phlebitis and neurological manifestations showed no significant difference in patients with and without HLA-B51. Ophthalmologic manifestations were seen in 52% of patients having B51 and in 42% of patients lacking it (χ2: 4.451, P = 0.035). Considering different lesions of ocular manifestations separately, no significant difference was found regarding the presence or absence of B51. Pathergy phenomenon was detected in 55% of B51 positive patients and in 45% of B51 negative patients (χ2: 4.111, P = 0.043). It seems that HLA-B51 may play a role in the pathogenesis of Behçet’s disease, but cannot be used as predictive value for the occurrence of organ involvement, except for the eye. © 2008 Tehran University of Medical Sciences. All rights reserved. Acta Medica Iranica 2008; 46(6): 507-510. Key words: Behçet’s disease, HLA typing, HLA-B5, HLA-B51