本研究はクラリスロマイシン(CAM)の少量長期投与の効果を評価する為にデザインされた.対象は75名の16歳以上の慢性副鼻腔炎患者であった.うち58名はCAMを1日200mg, 3ヵ月又は6ヵ月間投与された.他の17名はエリスロマイシン(EM)を1日600mg, 3ヵ月間投与された.自覚症状と他覚所見による治療効果は著効,有効,やや有効,無効,悪化に分類した.著効と有効とを併せた有効率は3ヵ月のCAM投与期間中は投与期間の増加に従って,有効率は上昇した.EMでも同様の傾向が認められた.投与3ヵ月目のCAMの有効率は44.5%, EMのそれは25.0%であり,両者間の有効率に差を認めなかった.このCAMの有効率について慢性副鼻腔炎に対する他の治療法の有効率と比較検討した This study was designed to evaluate the effectiveness of a long‐term and low dose adnlinistration of Clarithromycin (CAM) in chrOnic sinusitis(CS).The subiectｓ of this study were 75 patients with CS aged more than 16 years old. Fifty- eight patients were adnlinistered 200 mg of CAM per day for 3 or 6 months. Seventeen patients received 600 rng of Erythrornycin (EM) per day for 3 rnonths.The overall clinical efficacy determined by subjective symptoms and rhinoscopic observations was classified into excenent, good,fair, poor and worse categories.The general effectiveness that includes both excellent and good categories was tending to increaseup to the 3 months of the adrninistration period of CAM. The sirnilar observation was exist in the EM adrninistration. On the 3 months of adrninistration period, the general effectiveness of CAM and EM was 44.5% and 25.0% respectively, and this difference was not statistically significant. The general effectiveness of CAM was discussed in relation to that of other therapeutic methods for CS.