To assess the expression of Bcl-2 protooncogene in premalignant and malignant uterine cervix lesions.To establish the role of this protooncogene in uterine cervix carcinogenesis, we examined 69 tissue samples of low grade cervical squamous intraepithelial lesions (SIL) (n=16), high grade SIL (n=11), portio vaginalis uteri (PVU) carcinoma in situ (n=11) and PVU invasive carcinoma, stage IA-IIA (n=13) (study group) and 18 samples without SIL or malignancy (control group). The expression of Bcl-2 was detected immunohistochemically using a monoclonal antibody. Fisher's exact test (p <0.05) was used to assess statistical significance. By establishing the sensitivity and specificity of the test, the level of reliability of these analyses was determined as a possible screening method for early detection of changes in the uterine cervix.Overexpression of Bcl-2 was found to increase in direct relation to the grade of the cervical lesions. Statistically significant difference was found in the frequency of overexpression in patients with high grade SIL (6/11, p=0.006), PVU carcinoma in situ (5/11, p=0.018) and PVU invasive carcinoma (6/13, p=0.012), in relation to the control group. High sensitivity was of great diagnostic significance for the detection of these types of changes in the uterine cervix. On the basis of high predictive values it can be said that in patients with Bcl-2 overexpression there is a great possibility that they have premalignant or malignant changes in the uterine cervix.Our results indicate that overexpression of Bcl-2 may play an important role in cervical carcinogenesis. However, more extensive series of samples is required to establish the prognostic significance of Bcl-2 in cervical carcinogenesis.