We sought to review our kidney transplant biopsy experience to assess the incidence, type, presenting symptoms, and timing of renal transplant biopsy complications, as well as determine any modifiable risk factors for postbiopsy complications. This is an observational analysis of patients at the University of Wisconsin between January 1, 2000, and December 31, 2009. Patients with an INR ≥1.5 or platelet counts less than 50 000 were not biopsied. An 18-gauge needle was used for biopsy. Over the study period, 3738 biopsies were performed with 66 complications (1.8%). No deaths occurred. A total of 0.7% were mild complications, 0.7% were moderate complications, 0.21% were severe complications, and 0.19% were life-threatening. Most complications occurred within the 4-h postbiopsy period, although serious complications were often delayed: 67% of complications requiring surgical intervention presented greater than 4 h after biopsy. Biopsy within 1 week of transplant had a 311% increased risk of a complication. Postbiopsy reduction in hematocrit and hemoglobin at 4 h was associated with a complication. In conclusion, life-threatening complications after renal allograft biopsy occurred in 0.19% of patients. Most complications occurred within 4 h postprocedure; however, many serious complications occurred with a time delay after initially uneventful monitoring. The only clinically significant laboratory predictor of a complication was a fall in the hematocrit or hemoglobin within 4 h. Patients biopsied within a week of transplant were at the highest risk for a complication and should therefore be most closely monitored.