To evaluate the diagnostic usefulness of simultaneous determinations of carcinoembryonic antigen (CEA) and squamous cell carcinoma antigen (SCC-Ag), we studied 25 patients with lung carcinoma and 12 with nonmalignant lung diseases. The measurements were made in serum and bronchoalveolar lavage (BAL). The results showed that positive rates with lavage CEA and SCC-Ag in lung carcinoma patients were higher in comparison with those markers in serum. The combination of lavage CEA and SCC-Ag taken together with the results of bronchoscopy (histology and cytology) showed the highest discriminating power between malignant and nonmalignant lung diseases. The sensitivity of bronchoscopy increased from 48 to 84% with at least 1 positive marker. It appears that the simultaneous determination of CEA and SCC-Ag levels in serum and BAL in lung carcinoma patients may be of considerable importance in diagnosis.