We evaluated the role of antimicrobials in the treatment of chronic maxillary sinusitis in children with chronic cough. At the first visit 216 of 276 cases with chronic cough had radiologically abnormal maxillary sinuses (78.3%). By the Waters x-rays around 50 cases each were assigned randomly to four groups; among them, 48 cases were given an amoxicillin, 51 cases were given trimethoprim-sulfamethoxazole (TMS), 53 cases were given amoxcillin plus TMS and 50 cases were given expectorant plus decongestant (control) group. Thus, 202 children were included for data analysis. Treatment was given for two weeks in each group. The group treated with antimicrobials had a significantly higher cure rate than that of expectorant plus decongestant group (P<0.001). Most of the patients who had roentgenographic improvement have successfully recovered from the chronic cough and the other cardinal signs of chronic sinusitis.