Analysis of 18 patients who suffered recurrent urolithiasis after anatrophic nephrolithotomy is presented. These patients form a subgroup of 80 patients who underwent 100 consecutive extensive anatrophic nephrolithotomies between 1967 and 1972. Careful documentation of the 18 patients who had recurrent calculi was done in an effort to delineate the causative factors. The recurrence interval varied from less than 6 months to more than 8 years during an over-all followup period of 9.94 years. Marked differences in the characteristics between 14 male and 4 female patients were noted. In the male patients a significant relationship among recurrent staghorn calculi, anomalous urinary drainage and Pseudomonas urinary tract infections was noted. The female patients had recurrent or persistent urinary tract infections or undiagnosed metabolic problems as the primary reason for the recurrent urolithiasis.