OBJECTIVE: ICSI is generally performed using PVP, a water-soluble polymer, as a viscous agent, in order to facilitate the procedure. However PVP is not biodegradable and potentially carcinogenic (Barak et al.2001). Hyaluronic acid (HA), a natural compound secreted by cumulus cells has been proposed to replace PVP, as it helps selection of the best sperm before ICSI (Parmegiani et al, 2009). DESIGN: Historic comparison of 2 cohorts of ART patients. MATERIALS AND METHODS: All physiologic ICSI using HA (Spermslow, Medicult Denmark) cycles from January to December 2009 (group A, n=2014) were compared to those of the same length of time before HA use (group B, n=1920). We compared the numbers of embryos (obtained, top, transferred), and the clinical pregnancy rates (PR), globally and taking into account women's age and cycle rank. RESULTS: There was no difference in patients' age (35.2 and 35.3 yrs) and cycle number. More oocytes were retrieved/injected and more embryos cleaved in group B. However, cleavage rate was almost identical, and, even if the number of embryos per transfer was lower (p<0.01), PR was slightly but not significantly higher in group A. This was confirmed by a multivariate analysis (OR for AH=1.10, 95% CI=0.95-1.27).Tabled 1GroupA (AH)B (PVP)Age≤ 37≥ 38≤ 37≥ 38p (A vs B)N13806241359567Injected oocytes7.2 ± 4.605.0 ± 3.77.8 ± 5.15.6 ± 3.70.001Cleaved embryos4.7 ± 3.53.3 ± 2.95.0 ± 3.93.5 ± 2.90.01Cleavage rate (%)64.7 ± 27.564.4 ± 31.764.2 ± 27.062.2 ± 30.8NSTop embryos2.8 ± 2.32.2 ± 1.82.7 ± 2.12.2 ± 1.6NSTransferred embryos1.9 ± 0.72.1 ± 0.12.0 ± 0.72.3 ± 1.00.01PR/OPU %30.716.429.015.9NS Open table in a new tab CONCLUSION: Beside its positive effect in eliminating a potentially dangerous non-biodegradable compound (PVP), hyaluronic acid can be used without hampering ART results.