The aim of this study was to evaluate the level of asymmetrical dimethylarginine (ADMA) levels before gonadotrophine treatment and on the day of oocytes retrieval in order to determine whether ADMA can be used as a predictive marker for implantation success in in vitro fertilization (IVF) cycles. Forty-four unexplained infertile patients were included in the study. Controlled ovarian hyperstimulation was performed using the recombinant follicle-stimulating hormone (FSH) with the standard long protocol for all patients. ADMA and E2 were measured at the beginning of the ovulation induction and on oocyte retrieval day. The primary outcome was the difference in ADMA levels in implantation positive and implantation negative women. At the beginning of the ovulation induction, the mean ADMA levels were 1553 μmol/L and 1.464 μmol/L in the implantation positive and negative groups, respectively. There was no statistically significant difference between groups (p: 0.90). On the day of oocyte retrieval, the mean ADMA levels were 1173 μmol/L and 1170 μmol/L in the implantation positive and negative groups, respectively. There was no statistically significant difference between groups (p: 0.97). In conclusion, ADMA levels before gonadotrophine treatment and the day of oocytes retrieval cannot be used as a predictive marker for implantation success in IVF cycles.