Introduction: The most efficacious and commonly applied anesthetic technique for prostate biopsy is periprostatic block. In a previous publication, the creation of a 'hypoechoic space' at the injection site was described. This was reported to be a routine and essential part of the technique in various subsequent series. We were interested in assessing the incidence of the formation of such a hypoechoic area, and more importantly, whether it had any impact on pain management. Materials and Methods: One hundred and eleven consecutive patients were prospectively evaluated. Local anesthetic consisted of 2.5 ml of 2% lidocaine for each side of the prostate. Infiltration was done within the neurovascular space at the base of the prostate just lateral to the junction between the prostate and the seminal vesicle. The creation of a hypoechoic nodule was recorded in three categories: no formation, unilateral or bilateral formation. Three groups were compared regarding the intensity of pain using a numeric analog scale. Results: No hypoechoic area was formed in 30 (27%) patients. A unilateral nodule was created in 40 (36%), and a bilateral nodule was seen in 41 (37%) patients. The median pain scores were 3.3, 2.5 and 1.3 for the no hypoechoic wheal, unilateral and bilateral wheal groups, respectively (p < 0.0001). Conclusion: Our results suggest that the creation of a hypoechoic space with anesthetic infiltration for prostate biopsy is indeed an important aspect of the technique with regard to pain control; however, it may not be accomplished in every case. Copyright (C) 2006 S. Karger AG, Basel.