Abstract Objectives: To analyse I/D polymorphism of ACE gene in women with diagnosed endometriosis and to determine the correlation of the identified genotypes with the stage of the disease and its clinical picture. Material and methods: The analysis of ACE I/D gene polymorphism was performed in a group of 121 women with endometriosis and in the control group of 122 women. In the study group the stage of the disease, number of pathological foci, occurrence of chronic pain in pelvis minor and infertility were taken into consideration. Results: In the study group the following distribution was found of ACE gene genotypes: II – 25.62%, ID – 47.93%, DD – 26.45%, whereas in the control group: II – 35.25%, ID – 41.80%, DD – 22.95%. The comparison of the frequency of analysed genotypes and alleles between the study and control groups did not demonstrate statistically significant differences (p>0.05). Similarly no correlation was found for these parameters when the four stages of the disease acc. to rAFS (p>0.05) were compared. In the study group the frequency was compared of the analysed ACE gene genotypes and alleles in women with infertility (n=59) and in fertile women (n=62). The comparison of these parameters did not demonstrate statistically significant differences between the analysed groups (p>0.05). The frequency of genotype II was 17.07%, ID – 46.34% and DD – 36.59% in women with endometriosis complaining of pain (n=41). In the group of women with endometriosis without pain the frequency of the investigated genotypes (II, ID, DD) was respectively: 26.53%, 59.18%, 14.29%. DD genotype and D allele were more frequent in patients with pain complaints (p<0.05). Conclusion: In analysed population no association was found of ACE I/D polymorphism and the prevalence of endometriosis, its stages or the number of disease foci. However, the association of DD genotype and D allele with the occurrence of pain within pelvis minor in women with endometriosis was found.