Background/Aims: To improve procedural skill competence in real-time ultrasound-guided renal biopsy, we have developed an inexpensive simulation tool (a porcine kidney inserted under a turkey breast) that mimics biopsy conditions in human patients in terms of kidney size, depth, echogenicity and overall structural characteristics. This study investigated the utility of this simulation tool for improving trainees' confidence in performing renal biopsy and biop- sy-associated bleeding complications. Methods: We have quantitatively assessed the confidence level of renal fellows before and after their initial renal biopsy simulation training. Subsequently, we determined the effect of this simulation training on trainees' procedural competence by comparing outcomes of clinical renal biopsies performed by fellows that did versus those who did not participate in the simulation training. Results: We show that renal biopsy simulation has improved the confidence level of trainees (23.4 presimulation to 70.3 postsimulation on a 0-100 scale; p = 0.001; η2 = 0.69). The improvement in trainees' confidence did not vary across their prior experience performing renal biopsies (η2 = 0.23; p = 0.060). Additionally, fellows who participated in the simulation training demonstrated improved competence in performing the renal biopsy procedure in patients. Successful retrieval of renal tissue per pass was 94% (vs. 73% in fellows who did not participate in this simulation training; p = 0.002) and procedure-related blood loss was reduced as indicated by smaller postbiopsy versus prebiopsy hematocrit decline (1.18 vs. 2.68; p = 0.049). Conclusion: Renal biopsy simulation training may improve trainees' confidence and reduce the severity of biopsy-associated bleeding complications in patients. Copyright © 2012 S. Karger AG, Basel.