PURPOSE: The aim of this prospective, randomized study was to compare the results obtained in ICSI with two culture media, P-1 (Irvine Scientific) and IVF-50 (Scandinavian IVF Science). METHODS: A total of 182 patients undergoing ICSI treatment were randomly included in this study and divided in two groups: Group I: P-1 medium (n = 91) or Group II: IVF-50 medium (n = 91). All the embryos were transferred on the second day. RESULTS: Patient age did not differ (p = .29) between Group I (34.8 +/- 4.8) and Group II (34.0 +/- 4.5). The number of oocytes retrieved from Group I (10.6 +/- 6.7) was also similar (p = .49) to that retrieved from Group II (11.1 +/- 6.4). In addition, there was no difference (p = .25) in the number of oocytes retrieved at metaphase II between Group I (7.9 +/- 4.6) and Group II (8.7 +/- 4.6). Normal fertilization rates, abnormal fertilization rates, and cleavage rates were similar (p = .62, p = .48, and p = .9, respectively) between Group I (68.4 +/- 23.3%, 6.7 +/- 10.3%, and 98.7 +/- 4.6%) and Group II (65.3 +/- 26.2%, 9.0 +/- 13.8%, and 98.9 +/- 3.9%, respectively). The embryo score was also similar (p = .62) for both groups (Group I: 31.9 +/- 14.0 and Group II: 33.4 +/- 15.8). There was no difference in the number of embryos transferred (p = .69) between Group I (2.8 +/- 1.0) and Group II (2.8 +/- 1.1). In addition, pregnancy rates/puncture, pregnancy rates/transfer, implantation rates, and abortion rates were also similar for Group I (36.2%, 37.0%, 17.4%, and 12.1%, respectively) and Group II (31.8%, 33.7%, 15.8%, and 10.3%, respectively) (p = .64, p = .75, p = .72, and p = 1.0, respectively). CONCLUSIONS: There were no differences in the results obtained with culture media P-1 (Irvine Scientific) and IVF-50 (Scandinavian IVF Science) for ICSI and embryo culture.