Objective Acute fatty liver of pregnancy (AFLP) substantially contributes to maternal and neonatal morbidity and mortality. The aim of this study was to investigate angiogenic profiles by measuring soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PLGF) in pregnancies compromised by AFLP and to compare them to those complicated by HELLP (haemolysis, elevated liver enzyme, low platelet) syndrome. Methods In pregnant patients affected by AFLP or HELLP syndrome sFlt-1 and PLGF serum levels were measured. To assess the diagnostic potential of these angiogenic markers in AFLP as well as discriminating it from HELLP syndrome, non-parametric tests were used and receiver-operating-curves (ROC) were calculated. Results Six cases with AFLP and 48 women with HELLP syndrome were included into the study. Patients with AFLP showed significantly higher sFlt-1 levels (median: 57570pg/ml [range: 31609-147170pg/ml]) than patients with HELLP syndrome (9713pg/ml [1348-30781pg/ml ; p<0.001). PLGF serum levels were increased in patients with AFLP compared to those with HELLP syndrome (197 pg/ml [127-487pg/ml] versus 40 pg/ml [9-644pg/ml], respectively, p<0.01,). sFlt-1/PLGF-ratios were not significantly different between AFLP and HELLP syndrome patients (192 [157-1159] versus 232 [3-948], respectively, NS). A sFlt-1 cut-off value of 31100pg/ml allowed differentiating between these two diseases with a sensitivity and specificity of 100%. Conclusions AFLP is associated with very high serum levels of sFlt-1. Besides the suggested Swansea criteria to diagnose AFLP a sFlt-1 value above 31100 pg/ml may be also an additional biochemical feature improving discrimination between AFLP and HELLP syndrome. Funding:NA Keywords:AFLP, HELLP syndrome, preeclampsia, sFLT-1, PLGF