Beta-human chorionic gonadotropin (hCG) is normally produced and secreted by trophoblastic cells in pregnancy, by tumors arising from those cells and by a wide variety of tumors of nonendocrine origin. Gonadotropin is produced and secreted by various tissues (stomach, pancreas, ovary, etc.) and the incidence of ectopic secretion varies between 0 and 43%. Our report is an attempt to evaluate the incidence of high plasma beta hCG levels in 101 patients with gastrointestinal malignant tumors. The results revealed negative beta hCG in the control samples, while in the studied patients 41 were positive for beta hCG (44.4%). Three samples from oesophagus squamous cell carcinoma were positive. Twenty-five out of 69 with colorectal carcinoma had raised serum beta hCG (36.8%). Gastric carcinoma showed positive beta hCG in 52% of the patients. Among all the patients high beta hCG levels were far more common in those with positive lymphnodes (P less than 0.05). The beta hCG levels decreased with colorectal carcinoma tumor size and with smaller tumors there was the probability of increasing positive serum measurements (P less than 0.05). The patients with adenocarcinoma of the stomach showed good statistical correlation between stages of the disease at the operation time to beta hCG levels. In our opinion this serological assay will become one of the markers to be added to our armamentarium in the evaluation of patients with gastrointestinal malignant tumors.