Pregnancy rates (PR) are high from transfers with fresh embryos (ET) with cellular division, Day 1 after follicle aspiration (Early Cleavage -EC). We were also interested in further benefits of cycles resulting from cryopreserved (cryo) embryos. Our purpose was to describe the incidence of embryo freezing and any resulting pregnancies from EC/cryo cycles. Retrospective analysis of a prospective, non-randomized study. Part 1: A total of 713 IVF/ICSI patients undergoing IVF or ICSI in our center (from 2005 through January, 2006) were included. In 514 cycles, all embryos per patient were evaluated on Day 1 for fertilization and later for EC. The best quality embryos (with or without EC), were selected for ET on Days 2 or 3, based on published criteria. Part 2: Embryos selected for freezing (Days 3, 4, or 5) were only Grade 1 and 2. Day 3 and 4 embryos were frozen in culture medium + 1.5 M DMSO, using a controlled, step-wise method. For any subsequent cryo/ET cycle, usually 1-2 embryos were first thawed at room temperature (RT), then in a 0° C water bath for 10 min. and finally in decreasing levels of DMSO. All embryos were allowed to develop overnight before ET. Day 5 embryos were frozen and thawed according to Menezo (in a glycerol/sucrose based medium). Pregnancy following fresh or cryo cycles was defined as a positive urinary test 15 days after FA. Differences between EC, EC/cryo and Control groups were analyzed and values with p < .05 were considered significant. Select data are expressed as mean ± STD. Part 1: Three groups of patients were analyzed. Those with one or more EC embryos in the cohort (Group 1, n=275), those with no embryos with EC at the time of evaluation (Group 2, n=239) and those not checked for EC (Group 3: NC; control, n=199). There were no differences in the type of procedure performed (IVF or ICSI), the time to EC evaluation (25.8 ± 1.8 hrs) or in the number (1.86 ± .53) or quality (1.8 ± .62) of the embryos transferred between the three groups. Part 2: 160 patients, not pregnant from fresh ET, underwent a subsequent cryo cycle. Patients in Cryo Group 1 (+EC, n=76) were younger, than those from Cryo Groups 2 (-EC, n=53) and 3 (NC, n=41) (33.8 4.6 vs. 35.0 ± 4.1 and 34.6 ± 4.2 yrs, respectively; p< .05). Results from both the fresh and cryo cycles are listed in Table 1.Tabled 1*Survival rate per thaw with ≥ 1 embryo surviving A vs B p< .05; Cryo PR/ET: a vs. b (p< .03); % Cryo + Fresh PR): p< .05 When the “Checked” groups (± EC) were combined and compared with NC, there was a significant increase in cryo PR/ET from the NC (Group 3: see Table 1) than those checked for EC (± EC: 30.0%; p< .04). *Survival rate per thaw with ≥ 1 embryo surviving A vs B p< .05; Cryo PR/ET: a vs. b (p< .03); % Cryo + Fresh PR): p< .05 When the “Checked” groups (± EC) were combined and compared with NC, there was a significant increase in cryo PR/ET from the NC (Group 3: see Table 1) than those checked for EC (± EC: 30.0%; p< .04). The higher pregnancy rate as result of a better selection in the fresh cycle is, in part, offset by a lower pregnancy rate in frozen cycles where no EC has been assessed. The true added value of cryopreservation can only be determined after thawing all embryos, even if the fresh cycle resulted in an ongoing pregnancy, as many embryos are still frozen.