Intracytoplasmic sperm injection (ICSI) guarantees high fertilization rates and could theoretically lead to higher implantation rates as well. Furthermore injection into oocyte creates a hole in the zona pellucida similar to the procedure of assisted hatching. We were therefore interested to assess such a potential benefit for infertile IVF patients without male factor.Open randomized prospective study according to the rules "Good Clinical Practice" with informed consent of the patients and institutional review board approval. Ninety-one consecutively seen patients with tubal infertility or hostile cervical mucus were randomized to undergo either ICSI (44 patients) or IVF (45 patients). In two patients fertilization of oocytes failed and so a repeated ICSI had to be performed. All these patients were stimulated with the same protocol, using the gonadotropin releasing hormone-agonist (GnRH-a) buserelin acetate in an ultrashort flair-up protocol together with pure follicle stimulating hormone (rFSH). The two study groups did not differ in terms of age, BMI, and all baseline hormone levels.The total pregnancy rate was 42% in the normal IVF group with 33% ongoing pregnancies. The ICSI group had a total pregnancy rate of 39% with 23% ongoing pregnancies. The implantation rate per transferred embryo was higher for normal IVF but not significant (18% versus 11%). The variables, fertilization rate, age, body mass index, baseline hormone levels, endometrial thickness, embryo score, and the highest grade embryo per transfer were very similar in both groups.ICSI should be applied only when conventional IVF fails, that is, for male factor patients and for patients with unexplained infertility.