PURPOSE: To identify biomarkers that prospectively predict IVF cycle cancellation. METHODS: In this prospective study, sera were obtained prior to any intervention, from women about to undergo an IVF cycle. The sera were assayed by ELISA for levels of insulin-like growth factor (IGF)-1, IGF-2, IGF binding protein (BP)-1, and soluble fms-like tyrosine kinase (sFLT-1). The cancellation or progression of the IVF cycle was subsequently obtained by chart review. Associations between serum components and outcome were analyzed by the Mann-Whitney test. Receiver operator curves were constructed to evaluate the strength of the correlations between biomarkers and cycle cancellation, as assessed from the area under the curve (AUC). RESULTS: A total of 205 women were included. Twenty-seven (13.2%) cycle cancellations due to poor response were recorded. Women with a cancelled cycle had reduced anti-Mullerian hormone (AMH) values (p < 0.001) and antral follicle count (p = 0.003). There were no significant differences between the two groups with regard to age and BMI. Median concentrations of IGF-1 and sFLT-1 were elevated in sera from women whose IVF cycles were cancelled as compared to those with ongoing cycles (p = 0.015 and p < 0.001, respectively); AUC for IGF-1 and sFLT-1 were 0.67 and 0.75, respectively. Concentrations of sFLT-1 remained significantly higher in patients with cancelled cycles even after controlling for AMH levels. There were no differences in IGF-2 and IGFBP-1 levels between the two groups. CONCLUSIONS: Measurement of circulating IGF-1 and sFLT-1 levels prior to initiation of an IVF cycle has the potential to identify women whose cycles have an increased likelihood to be subsequently cancelled.