Endoscopy complemented by directed biopsies and exfoliative cytology was performed on 593 patients with different gastric lesions. Of the 194 cases of proven adenocarcinoma of the stomach, cytology was positive for malignancy in 176 (90.7%) and yielded the highest diagnostic rate. Endoscopy correctly diagnosed 171 cases (88.1%), and biopsy had the lowest accuracy, 153 cases (78.9%). The combined use of the three techniques increased the positive diagnosis to 185 adenocarcinomas (95.4%). Only three early gastric cancers were diagnosed by the combined methods, with only cytology positive in all three cases. There were five (1.3%) false-positive cytologic reports, principally due to benign gastric ulcers. It is concluded that these techniques have a complementary function in distinguishing benign from malignant gastric lesions. Since the value of endoscopic signs is limited, biopsy and cytology should always be performed. Exfoliative cytology plays an effective diagnostic role in cancer of the gastrointestinal tract and should be used more frequently by gastroenterologists, who, however, should be aware of the risk of false-positive results.