The A- and B- types of Human Leucocyte Antigens (HLA) were examined in a group of Greek patients with a diagnosis of chronic bronchitis. The results were compared to those of 400 healthy unrelated controls (smokers and non-smokers) from the same population. A statistically significant increase of HLA-A1 and HLA-B17 was noted; a similar increase was also noted when only healthy smokers were utilized as a control group. These results support the hypothesis that genetic factors are also involved in the pathogenesis of this common disease.