In this study the chemotactic activities of neutrophils and monocytes were evaluated in patients with chronic sinusitis as compared to a control group. Leukocyte chemotaxis was measured with a micropore filter method in blood samples taken from 26 patients with chronic sinusitis and 10 volunteers. A statistically significant impairment of leukocyte chemotaxis capacity in patients with chronic sinusitis was found. It is concluded that a functional disorder of leukocytes may play a role in the progression of the disease into a chronic state.