Heat shock proteins (Hsp) are highly expressed in many malignant human tumors, including tumors of the genital tract. One of the Hsps strongly associated with the process of cancerogenesis is Hsp27. The presence of Hsp27 and anti-Hsp27 in the sera of patients with ovarian carcinoma is still a new research field, and papers contain contradictory results. The aim of this work was to study the concentrations of anti-Hsp27 immunoglobulin G antibodies in the sera of women with ovarian cancer at different clinical stages and with different histopathological types of this cancer.Serum samples from 158 patients with ovarian carcinoma and 80 healthy women were investigated. The concentrations of anti-Hsp27 antibodies were determined by the enzyme-linked immunosorbent assay technique.The mean concentration of anti-Hsp27 antibodies in the patients with ovarian carcinoma was significantly higher than that in the control group. Analysis in relation to the stage of clinical progression showed that the less advanced the cancerogenesis process, the higher the concentration of the anti-Hsp27 antibodies is. The mean concentrations of the anti-Hsp27 antibodies in the patients with ovarian carcinoma were not significantly different in relation to the histological type of the cancer. The use of chemotherapy as a primary anticancer treatment in ovarian carcinoma did not cause a significant decrease in the concentration of anti-Hsp27 antibodies.An immunological response to Hsp27 is increased in women with ovarian carcinoma. Although the diagnostic concentrations of anti-Hsp27 antibodies have not been precisely defined yet, we believe that this may be a helpful diagnostic parameter particularly to detect early stages of clinical advancement of the disease.