Since the day ICSI was born in ART its a very interesting question what kind of fertilization method is the better way in patients with endometriosis: IVF or ICSI ? In cases of pathological sperm parameters the procedure is clear and every IVF laboratory will do the ICSI-procedure. But what kind of fertilization method is the better way to get the couple pregnant when the partner has a normal spermiogram ?In these cases are not much data available. Asking experienced IVF specialists the answer is, that the ICSI-procedure might be the better way. But they cannot answer that question with systematical data, it?s just due to their clinical experience. Because of the absence of data IVF-lab`s prefer to do half IVF-procedure and half ICSI-procedure. But they didn?t collect this data, and so those labs could only give you an estimated successrate, but not a clear answer.It`s the aim of this study to investigate the pro`s and con`s of IVF versus ICSI in cases of endometriosis. Included were women with endometriosis diagnosed by biopsy, having partners with normozoospermia. Those women had been stimulated with agonist- or antagonist protocol, and in cases of 6 or more oocytes after pick up, we divided them into two groups, the IVF-group, and the ICSI-group. The first finishing point of this study was the grading of the blastocystes on day 5, the second one the biochemical pregnancy rate.The result was a better fertilization, better blastocyst development and higher biochemical pregnancy rate in the ICSI-group.Yet the number of patients is too small to get a significant result, but there is an obvious tendency towards the ICSI-procedure.Of course we keep this study going on to collect more data, to get statistically significant results, to be able to make a recommendation which fertilization method has more benefit in infertility cases with endometriosis.