We report a case of interstitial pulmonary disease that occurred together with lymphocytic colitis during treatment with ticlopidine. The drug was prescribed for transient ischemic cerebrovascular accidents. Ticlopidine treatment was stopped, and a prolonged course of prednisone was necessary to treat the pulmonary and intestinal symptoms. So far, few cases of pulmonary side effects caused by ticlopidine have been reported. This case is unique in that interstitial lung disease evolved in parallel with colitis and caused severe hypoxemia. Special care should be taken when pulmonary symptoms appear in association with ticlopidine treatment.