A number of studies published recently focused on the putative role of leptin in the pathogenesis of various primary human malignancies. Current study was aimed at investigating ObR, PI3-kinase, phospho-Akt kinase and PTEN proteins expression in forty-five primary human endometrioid-type endometrial carcinomas (EC). ObR immunostaining was detected in 21 of 45 (47%) ECs, presented in almost 60% of well- and moderately-differentiated tumors compared to only 17% of poorly-differentiated neoplasms (P<0.05). Semi-quantitative histological score (H-score) ObR values were inversely correlated with patients' body mass index (R=-0.35; P=0.019). ObR expression was significantly higher in normal weight compared to overweight and obese patients (P=0.024). All slides displayed intense PI3-kinase immunoreactivity, whereas phospho-Akt kinase expression was reported in 96% (43 out of 45) cases. Fifteen (33%) ECs were negative for PTEN expression, nine (20%) showed heterogeneous immunostaining pattern, whereas 21 (47%) were PTEN-positive. There was a trend towards a higher phospho-Akt kinase intensity immunostaining in PTEN-negative compared to PTEN-positive cases, but the difference was not significant. There was no significant association between each PI3-K/Akt signaling pathway proteins immunostaining in endometrioid-type ECs. In conclusion, ObR expression is associated with histological grading and the weight of women affected by EC. The components of PI3-K/Akt kinase signaling pathway are expressed in most of the primary endometrioid-type endometrial neoplasms.