Introduction: The prostate biopsy guided by ultrasound is the method of choice for early diagnosis of prostate cancer, is a safe whose main trouble is that it feels discomfort during the procedure. Material and methods: From July 2004 until March 2005 we prospectively studied 114 patients who underwent transrectal ultrasound guided needle biopsy of the prostate, they were divided in two groups: in one group we used lidocaína gel 2% inside the rectum before the procedure and in the other group we did not use it. We compared the pain that patients felt during the procedure with a pain scale. Results: We did not find differences between both groups, but the patients in whom we used a new needle felt less pain than the patients in whom we used a re-esterilized one. Conclusions: The use of lidocaine gel intrarectal 2% before a prostate biopsy guided by ultrasound did not diminish the sensation of pain from the procedure in our patients, which was increased by the use of sterilized needles.