Introduction: Benign prostatic enlargement is the most common benign disease in men. The main cause for emergence of benign prostatic enlargement is sexual hormone testosterone. Under the influence of enzyme 5 alfa reductase testosterone turns into active dihydro testosterone, which is then combined with receptors and causes the growth of prostate. Benign prostatic enlargement can cause the lower urinary tract symptoms. One of the treatment options of lower urinary tract symptoms due to benign prostatic enlargement is treatment with medicaments – inhibitors 5 alfa reductase. Like any other medicament, this one can also have unpleasant side effects, between others reduced erectile function and smaller libido. Purpose: The purpose of this research is to find the correlation between medicament treatment of lower urinary tract symptoms due to benign prostatic enlargement and erectile function and consequently influence on the quality of life. We will research the influence of treatment with medicaments inhibitors 5-alfa reductase on the erectile function six months after the treatment. Work methods: We used descriptive research method with collecting, critical judgment and analysis of domestic and foreign literature. We used resources from Internet databases like CINAHL, Medline, catalogue COBIB.SI and from libraries of Health faculty in Ljubljana and intermunicipal library of Žalec. In the second part of the work a cross study was made, with help of a questionnaire. Results: Men with benign prostatic enlargement have problems with holding an erection already before starting the therapy with medicaments. After the therapy with inhibitors 5-alfa reductase the results of the research show that on the erectile function scale, there are no significant differences between first and second measurement, but on the erectile dysfunction scale expected differences occur – the functionality decreases. We also noticed that the independent variables of age and employment status have influence on the result of treatment with medicaments in the way that older participants in the study have more issues with erectile function than younger ones. Secondly, the men in retirement have more problem than employed men. There were no noticeable connections between the finished education and the profession of the participants. Discussion and conclusion: The results of the research were expected, according to the before consulted literature, where the side effects of treatment with medicaments inhibitors 5-alfa reductase were already mentioned. The effects that the treatment has on erectile function are that the function deteriorates, that is why it is important that we seek doctor assistance immediately after it occurs. The disease mainly manifests itself at older generation of men and it has a negative effect on erectile function already at the very beginning. Before starting the treatment the patients would need to be informed about the side effects of the medicamental treatment and they should be presented about other possibilities of treatment without side effects to erectile function.