Previous studies have demonstrated some significant differences in HLA allele frequencies in leukemic patients and normal subjects. In Moroccan leukemic patients, the frequency of HLA alleles has not already been determined. We have analyzed HLA class I and class II alleles and haplotypes in 62 Moroccan leukemic patients and 98 unrelated normal subjects using PCR-SSO method. Significant positive association with the disease, in patients compared to controls, was found for three alleles: HLA-B*44 (12.7% vs 6.6%; p = 0.02), HLA-DRB1*13 (11.8% vs 9.79%; p = 0.04) and HLA-DRB*01 (4.5% vs 10.7%; p = 0.05). Regarding haplotypes analysis, no significant association was found between patients and control groups. It is suggested that HLA-B*44 and HLA-DRB1*13 alleles may play a presumptive predisposing factor while the HLA-DRB*01 allele could be a protective genetic factor against leukemia.