Organ-preserving surgery has gained widespread acceptance within the international urological community through the last decade. In consequence, the question of radical vs. nephron sparing surgery for the treatment of renal cancer is increasingly discussed in a controversial way. Today, even advocates of a radical nephrectomy must admit that long-term results obtained through nephron sparing surgery are excellent. In consequence, heminephrectomy has become a standard treatment in patients with impaired renal function. However, in patients with a normal contralateral kidney, national and international guidelines still favor radical nephrectomy. An increased morbidity and doubts on the efficacy of heminephrectomy concerning tumor control are the key reasons behind this strategy. Within this analysis the authors stress the hypothesis that the actual differences between organ-preserving surgery and radical nephrectomy concerning survival are marginal if the requirements for heminephrectomy are met. Therefore, the actual controversy appears to be rather based upon assumptions and convictions than on actual facts. To definitively answer this question a prospective randomized trial is suggested, however, the problems of this study may not be underestimated.