Human leukocyte antigen HLA-B51 is the most strongly associated gene with Behçet disease (BD) in different ethnic populations. We analyze the influence of HLA-B alleles in BD predisposition in Moroccan population and its association with clinical manifestations. The HLA-B phenotype frequencies were analyzed by serologic HLA class I typing and by polymerase chain reaction sequence-specific oligonucleotide (PCR-SSO) reverse dot blot hybridization in 120 unrelated Moroccan patients: all of whom fulfilled the international study group criteria for Behçet's disease, and in 112 ethnically matched healthy controls. Besides HLA-B*51 allele (20%), a significant increased frequency of the HLA-B*27 allele was found in Moroccans patients with Behçet's disease when compared to controls (13.3% of patients versus 2.7% of controls, chi square = 8.75, OR = 5.59, 95% IC [1.58-19.75] and particularly in the patients who presented an anterior uveitis (25% vs. 5.5%, p < 0.005).