OBJECTIVES: Abnormal uterine bleeding (AUB) is caused by derangement of physiological processes of tissue growth, shedding and regeneration. It is known that interplay between metalloproteinases (MMP's) and tissue inhibitors of metalloproteinases (TIMP's) may play a crucial role in its occurrence. AIM: To define if expression of proMMP-2, MMP-2 and TIMP-1 in endometrium of women with AUB is dependent on steroid sex hormone concentration and histopathological picture. MATERIALS AND METHODS: Endometrial scraps were taken from 21 women with AUB and 19 controls. Samples were evaluated in light microscopy by a certified pathologist. Activity of proMMP-2 and MMP-2 proteins levels were evaluated by gelatin zymography and TIMP-1 by reversed zymography. The results has been correlated with serum estradiol and progesterone concentrations in linear regression model. RESULTS: Expression: of proMMP-2 in endometrium of women with AUB is correlated with estradiol concentration and inversely correlated with progesterone levels. It was significantly higher in women with dysfunctional endometrium (p<0.001). Expression of MMP-2 was highest in women with endometrial polyps and longer bleeding (p<0.01), while expression of TIMP-1 was independent from hormone concentration. CONCLUSION: Lack of correlation between proMMP-2 and MMP-2 levels suggest different pathway of their activation in AUB. ProMMP-2 is up regulated by estradiol and down regulated by progesterone while MMP-2 levels increase with the length of bleeding.