Few investigators have simultaneously evaluated leptin, soluble leptin receptor (SLR) and leptin gene polymorphisms in preeclampsia cases and controls. We examined these three biomolecular markers in 40 preeclampsia cases and 39 controls. Plasma leptin and SLR concentrations were determined using immunoassays. Genotype for the tetranucleotide repeat (TTTC)(n), polymorphism in the 3 -flanking region of the leptin gene was determined using PCR. Alleles of the polymorphism were characterized by size distributions [short repeats (class I); and long repeats (class II)]. Logistic regression was used to calculate odds ratios (OR) and 95 % confidence intervals (CI). Leptin concentrations were higher in our cases than in the controls (53.1 4.7 vs. 17.7+/-2.4 ng/ml, p<0.05). SLR concentrations were slightly lower in our patients than in the controls (25.7+/-1.9 vs. 29.1+/-1.1 ng/ml, p>0.05). Elevated leptin (? 14.5 ng/ml) was associated with a 3.8-fold (CI 1.0-14.4) increased risk; whereas low SLR (< 28.5 ng/ml) was associated with a 6.3-fold (CI 1.7-23.2) increased risk of preeclampsia. The I/II genotype was associated with a 3.8-fold increased risk of preeclampsia (OR=3.8; 95 % CI 0.8-18.0); and the II/II genotype was not observed among our cases (0 % vs. 33 % p<0.001). Larger studies would be needed to confirm and further clarify the relations between functional variants in the leptin gene and preeclampsia risk.