The incidence of second primary lung cancer (SPLC) seems to have increased in recent years. In our series that included more than 4000 patients with lung cancer and 1600 operations, we observed 26 cases of SPLC up until June 1999. We considered the standard criteria accepted by most authors for the selection. Characteristics of patients and tumors at the time of the first operation were compared with the statistical data of our general series. Age, sex, performance status and smoking were all considered, as well as cancer site, histology, stage and type of first surgical operation. No significant independent factor could be identified for the prediction of a new tumor at that time. A second operation was possible in 16 cases: two patients died in the postoperative period, two survived for 12 and 24 months, respectively, 12 are still alive 8-87 months after the new resection. The high rate of surgical cases (16/26 = 62%) and a good survival rate is clearly correlated with an early diagnosis of SPLC.