Sialic acid residues perform important roles in both physiological and pathologic processes. Our aim was to measure the levels of sialic acid in the follicular fluid of women undergoing in vitro fertilization (IVF) and to assess correlations between IVF parameters and sialic acid levels. All women meeting the inclusion criteria underwent gonadotropin-releasing hormone agonist treatment and during oocyte retrieval, follicular fluids of mature follicles were collected and pooled for each patient. Correlation analysis was made between sialic acid levels and oocyte quality. Eighty-seven patients meeting the inclusion criteria were enrolled. In terms of oocyte quality and sialic acid, follicular fluid total sialic acid (FF-TSA) levels positively correlated with germinal vesicle oocytes and metaphase I oocytes. In terms of clinical parameters, no correlation between sialic acid levels and body mass index, serum levels of hormones, duration of infertility, and the total dose of gonadotropins was observed. The mean FF-TSA was 86.1±35.19 mg/dl in the clinical pregnancy positive group and was 73.64±22.15 mg/dl in the clinical pregnancy negative group. FF-TSA levels positively correlated with immature oocytes. This can be either as part of the normal oocyte maturation or as a compensatory mechanism against reactive oxygen species during the oocyte maturation process.