Seventy-two human primary endometrial adenocarcinomas (of stages II and III) were obtained from Croatia Human Tumor Bank. Enodmetrial carcinomas were pure or endometroid adenocarcinomas, composed entirely of glandular cells. Immunohistochemical tests were performed on formalin-fixed, paraffin-embedded tissue using the avidin-biotin-peroxidase method. Sections, cut at 4 µm, were subjected to a heat-induced epitope retrieval technique in 10 mM citrate buffer (pH 6.0) in an 850 W microwave for 10 min. Anti-IGF-2, a mouse monoclonal antibody (Upstate Biotechnologies, Lake Placid, NY, USA), was diluted 1:50, and incubated for 15–18 hrs. Anti-IGF-1R (Santa Cruz Biotechnologies, Santa Cruz, CA, USA), were diluted 1:100 and also incubated for 15–18 hrs. Detection was achieved using the DAKO LSAB 2 kit, according to manufacturer’s instructions. Negative controls were stained by substitution of the primary antibodies with non-immune mouse or rabbit immunoglobulins. Appropriate positive controls (thyroid gland tissue for IGF-1R, and Wilms’ tumor for IGF-2) were stained positively. The tumor cells showed strong diffuse cytoplasmic immunopositivity for IGF-2 and cytoplasmic and focal membranous reactivity for IGF-1R. The intensity of staining was arbitrary judged as weak (+), moderate (+ +), or strong (+ + +).