We report four cases that were pathologically diagnosed, after surgical resection, as inflammatory pseudotumors (IPT) of the lung in patients admitted to Fukuoka University Hospital between 1985 and 2001. On chest radiographs, one patient had a solitary nodular shadow, while the other three had multiple nodular shadows. Chest computed tomography (CT) was performed in 3 patients. All had at least one nodule attached to the pleura. In one case, multiple nodules that had been noted five years before and had disappeared later without treatment, had reappeared two months before admission. The tentative preoperative diagnosis was primary or metastatic lung cancer. Precise diagnosis of IPT totally depends on histological examination after surgical resection. IPT sometimes tends to grow aggressively, although it is histologically benign. Complete resection is the only treatment to avoid relapse.