The object of this retrospective cohort study was to determine if hCG levels correlate with ovarian hyperstimulation syndrome (OHSS) risk after adjustment for other risk factors during in vitro fertilization (IVF). We measured serum hCG approximately 12 h after hCG trigger in women undergoing 406 cycles of controlled ovarian hyperstimulation for IVF between June 2006 and December 2009. Serum hCG levels were measured 12 h after trigger. Bivariate logistic regression was used to assess the association between patient and cycle characteristics and OHSS. In our series, mild to moderate OHSS occurred in 9% (38/406), and severe OHSS diagnosed in 1.5% (6/406) of IVF cycles. OHSS risk was increased in younger women (<30 years old: adjusted odds ratio: aOR 2.46, 95% confidence interval: CI 1.14-5.34), increased number of oocytes (11-20: aOR 6.79, 95% CI 1.97-23.40; >20: aOR 17.55, 95% CI 4.84-63.70), and increase E2 levels (≥3,000 pg/mL: aOR 2.59, 95% CI 1.33-5.05), but was unrelated to hCG level (100-200 IU/L: aOR 1.53, 95% CI 0.60-3.91; ≥200 IU/L: aOR 1.42 95% CI 0.48-4.20). These results indicate that OHSS risk during IVF is unrelated to serum hCG level measured approximately 12 h after trigger.