The aim of the study was to determine unfavourable prognostic factors for patients with stomach adenocarcinoma after their surgical treatment through evaluation of prognostic indicators for cellular ploidy and proliferative activity.Material and methods. A group of 51 patients following surgical treatment due to stomach adenocarcinoma and discharged from our hospital between 1995-2000 were studied here. The material examined was encased in paraffin blocks. After histopathological verification, the tumour segments within these blocks were used for cytofluorometric analysis of DNA-ploidy according to Hedley's method.Results. In 41 (80.4%) stomach cancer patients (out of the total group of 51 patients), diploid tumours were found. No significant relationship between DNA ploidy and sex, age, symptoms, inherited susceptibility to a disease, tumour magnitude, grade of histological malignancy, or grade of clinical progression was observed. Generally, after the stomach cancer operation, the probability of five-year survival was 22.1% for patients with diploid tumours (DI=1.0), and 20% for the patients with aneuploid tumours (DI ± 1.0). The probability of 10-year survival was 19.2% for diploid tumours, and 10% for aneuploid tumours. These differences were not statistically significant (p=0.255).Conclusions. 1. Classical clinicopathologic factors are still the best prognostic criteria for the evaluation of long-term results of surgical treatment for stomach cancer patients. 2. Determination of DNA-ploidy and proliferative activity of stomach cancer did not decrease the gap between long-term results prognosis for surgical treatment and actual results.