Introduction. Evaluation of sexual function in men with prostate cancer (PCa) is of great importance, since treatment methods can influence on sexual function. Questionnaires allow to evaluate sexual function in men during the last month before the treatment. At the same time, the sexual life of a man who has developed PCa is still not studied. The experience of assessing the sexual constitution of men with newly diagnosed PCa is presented in the article.
Aim. To determine male sexuality from its first manifestations to the moment of PCa diagnosis, i.e. throughout the entire period of sexual activity, as well as to evaluate the relationship between sexuality and serum testosterone levels at the time of PCa diagnosis.
Materials and methods. A total of 87 patients aged 47–75 years diagnosed with PCa pf T1C-3bN0-1M0-1a, who independently answered the questions of the questionnaire "Integral assessment of male sexuality" (2009), were included in the study. All men underwent an examination for serum total testosterone.
Results. From the whole cohort, 90.8% of men were defined as hyposexual, and 9.2% had normal sexuality. Weak sexual constitution was found throughout the entire period of sexual life, but by the time of PCa diagnosis, it was even lower. 70.1% of patients had a total testosterone deficiency at the time of PCa detection. No reliable relationship was found between the reduced and normal sexual constitution and serum testosterone levels.
Conclusion. Most men with PCa have low sexual activity throughout their lives, a high incidence of testosterone deficiency at the time of cancer diagnosis. In addition, there is no relationship between serum testosterone levels and male sexuality.

Keywords: serum testosterone, male sexuality, male sexual constitution, prostate cancer