OBJECTIVES Low testosterone levels have been related to a higher diagnosis of prostate cancer (PCa). Hormonal levels have been related to poor prognosis factors in men with PCa, mainly after radical prostatectomy. Our aim was to determine the relationship between hormonal levels and PCa prognosis factors in men with PCa prior to the onset of treatment. PATIENTS AND METHODS We prospectively analysed 137 males diagnosed in our centre with PCa with 5 + 5 core prostate biopsies from February 2007 to December 2009. As part of our clinical protocol, we performed hormonal determination (testosterone and sex hormone binding globulin) following International Society of Andrology, International Society for the Study of the Aging Male and European Association of Urology recommendations. Free testosterone and bioavailable testosterone were calculated using Vermeulen's formula. Age, prostate-specific antigen (PSA), free to total PSA, PSA density, number of previous biopsies, digital rectal examination staging, Gleason score, percentage of tumour in the biopsy sample, bilaterality of the tumour and risk of progression group were prospectively recorded. RESULTS Higher testosterone levels were related to lower digital rectal examination staging (P = 0.02) and lower PSA level (P = 0.05). Higher testosterone was not related to lower Gleason score (P = 0.08). Testosterone was inversely related to PCa bilaterality (P < 0.01) and percentage of tumour in the biopsy (P < 0.01). High testosterone levels were found in patients allocated to the low risk of progression group and inversely (P = 0.03). In multivariate analysis, higher age and lower testosterone were related to higher D'Amico risk of progression. CONCLUSION Patients with PCa and lower testosterone levels have poor prognosis factors and higher tumour burden before treatment onset. These findings reinforce the idea that low testosterone levels pretreatment are related to a poor prognosis in PCa.