Drug resistance remains a major problem in the treatment of gastric cancer. In Turkey, gastric carcinoma is the second most common cancer and, because the rate of early diagnosis is low, chemotherapy plays an important role in the treatment of the disease. We aimed to investigate expression of the multidrug resistance-1 gene (MDR-1) and its relationship with multiple prognostic factors in gastric cancers. Between 1996 and 1998, a total of 55 patients (37 men and 19 women; median age 55 years) were studied. Sections from specimens of gastric carcinomas were immunohistochemically stained to detect P-glycoprotein (which is associated with MDR-1 expression). We found MDR-1 expression in 48 (87%) of the patients. None of the multiple prognostic factors, including histological type of tumour, correlated with expression of MDR-1. Patients who had low MDR-1 expression had better survival. We conclude that the expression of MDR-1 in gastric cancer is high in Turkey, and this may be related to poor prognosis.