Treatment of varicoceles became the most common treatment for male infertility merely on an empirical basis. However, in the age of evidence-based medicine it is surprising that only a few, and mainly recent, randomized controlled clinical trials with relevant outcome parameters have been published to allow adequate judgement of treatment effectiveness. Moreover, difficulties in study design could also be detected in most of these high-quality studies. Despite these difficulties and in contrast to the majority of uncontrolled studies on varicocelectomy, meta-analysis of these randomized controlled clinical studies involving 385 patients showed no significant treatment benefit and questions the common practice of varicocelectomy. Even the high-quality studies show conflicting results and therefore the topic of varicocele treatment will remain controversial and further randomized clinical trials should readdress this issue. For the time being, intervention by surgical or angiographic occlusion of the spermatic vein cannot be recommended.