Tumours from 45 patients with advanced gastric cancer were assessed by immunohistochemistry. Tissue sections were fixed in 10% buffered formaldehyde solution, embedded in paraffin and stained immunohistochemically with anti-human Ki-67 and PCNA antibodies. No correlation was found between Ki-67, PCNA protein expression, the age of patients and the localization of tumour. A significant, positive association was observed between the expression of Ki-67, PCNA and tumour differentiation and Lauren's classification. Also a strong correlation was found between lymph node involvement and the expression of Ki-67 protein. These data suggest that the expression of Ki-67, PCNA proteins were closely connected with the high grade of tumour malignancy.