The quality and frequency of mutations in PTEN gene were assessed in 59 carcinomas and 6 hyperplasias of the endometrium in women. Screening for mutations was done in all exons of PTEN gene by the PCR-SSCP analysis and DNA sequencing. Results were correlated with histological status and clinical features of endometrial carcinomas. In 45.8% (27/59) of carcinomas, 36 somatic mutations were detected in PTEN gene. In seven carcinomas, two mutations and in one carcinoma three mutations coexisted simultaneously. Moreover in 33.3% (2/6) of hyperplasia cases mutations were shown. Most identified mutations (57.9%) were present in exons 5 and 8, less frequently in exons 2 (15.8%) and 7 (13.2%) and they were least frequent in exons 1 and 3 (5.3% each). No mutations were found in exons 4, 6 and 9. Of all identified mutations, 73.7% of those resulting in truncated protein were present due to deletions, insertions and nonsense mutations. Missense mutations accounted for 13.2% of mutations and they were present only in exon 5. One point mutation (2.5%) was in intronic splice site. The remaining 10.5% of mutations were neutral polymorphisms. No statistically significant correlation were found between the frequency of PTEN gene mutations and the clinical stage of endometrial carcinomas. However, evident statistically significant, reverse correlation were observed between the frequency of mutations and the grade of morphological differentiation of the diseases (chi(2)=7.2393, alpha=0.0071). In conclusion, our data support the view that PTEN gene mutations are frequent events involved in development of endometrial carcinomas in women.