Intrauterine insemination (IUI) has been used for the treatment of infertility often as a first-line therapy. Its overall success varies with pregnancy rates/cycle ranging from 5-20%. Sperm processing is required prior to an IUI. Sperm preparation techniques such as density gradient separation (DG) and simple washing (SW) require the use of centrifugation to separate the sperm from the seminal plasma. DG yields a high concentration of motile sperm, relatively free of cellular debris and leukocyte contamination. However, this method is expensive and time-consuming with a low motile sperm recovery rate (20-70% of initial parameters). SW is a fast and inexpensive method of sperm separation using only a single centrifugation wash step. This technique concentrates all cells found in the original sample such as motile sperm, immotile sperm, cellular debris, and leukocytes. Despite the known differences in recovery rates and the ability of separating motile sperm from seminal contaminants, there is limited knowledge about the effect of the different sperm preparation methods on clinical outcomes. To evaluate the efficacy of DG and SW sperm preparation techniques on IUI clinical outcomes. Data on 600 subfertile couples undergoing IUIs at an academic center from 3/2017 to 4/2018 were retrospectively analyzed. Sperm was prepared with DG for 300 specimens and with SW for another 300 specimens. DG Method: Liquified semen was layered over 50:90% ISolate (Fujifilm) and centrifuged at 300g for 20 min. DG sperm pellet was resuspended in 5 ml Multipurpose Handling Medium (MHM; FujiFilm) and centrifuge for 10 min at 300g. This final step was repeated, and the final pellet was resuspended with MHM to a final insemination volume of 0.5 ml. SW Method: Liquified semen was added to 10 ml MHM and centrifuged for 10 min at 300g. SW sperm pellet was resuspended with MHM for a final insemination volume of 0.5 ml. There was no difference in interval between semen production and time of insemination between the 2 groups. Outcome measures: pregnancy rate (PR), livebirth rate (LBR), spontaneous abortion rate (SABR) (out of clinical pregnancies), and multiple pregnancy rate (MPR) (out of livebirths). Parametric and non-parametric tests were used as appropriate. Logistic regression was used to calculate odds ratios, controlling for age. P-values<0.05 were considered statistically significant. There were no significant differences in the demographic and semen analysis parameters between the two groups, except for higher sperm motility in the SW group (44.4% vs. 48.9, p:0.005) (Table 1). PR, LBR, SABR, MPR were not significantly different between the 2 methods: PR (14.7% vs. 16.7%, p:0.500), LBR (12.3% vs. 12.3%, p:1.000), SABR (14.0% vs. 19.6%, p:0.478), and MPR (8.1% vs. 13.5%, p:0.711), respectively for DG vs. SW. Odds ratios for the same rates yielded no significant results, after adjusting for age, as follows: [DG vs. SW, OR (95%CI)] PR [0.884 (0.567-1.379), p:0.588], LBR [1.032 (0.632-1.686), p:0.898], SABR [0.667 (0.215-2.066), p:0.482], and MPR [0.521 (0.112-2.430), p:0.407]. Our results demonstrate that DG and SW are equally effective methods for preparing sperm for IUIs.