Pre-eclampsia is one of the most serious disorders of human pregnancy and T helper type 1 (Th1)/Th2 imbalance plays a major role in its aetiology. The Th2 cytokine, interleukin (IL)-10, plays a significant role in the maintenance of pregnancy. The present study is aimed at understanding the role of IL-10 promoter polymorphisms (−1082 G/A; −592 A/C and −819 C/T) and their haplotypes in early-onset pre-eclampsia. A total of 120 patients and an equal number of women with normal pregnancy, from Government Maternity Hospital, Petlaburz, Hyderabad, India, were considered for the present study. A standard amplification refractory mutation system–polymerase chain reaction (ARMS–PCR) was carried out for genotyping followed by agarose gel electrophoresis. Appropriate statistical methods were applied to test for the significance of the results. It was found that the IL-10 −819 C allele (P = 0·003) and −592 A (P = 0·005) allele frequencies increased significantly in patients compared to controls. No significant difference was found with regard to −1082 promoter polymorphism. Haplotype analysis of the IL-10 single nucleotide polymorphisms (SNPs) revealed a significant association with ACC haplotype with a twofold increased risk in patients compared to controls. The frequencies of two common IL-10 haplotypes (GCC and ATA) did not show any significant difference. Further, the diplotype analysis revealed five genotypes: −1082A with −819C (P = 0·0016); −1082G with −819C (P = 0·0018); −819C with −592C (P = 0·001); −1082A with −592C (P = 0·032); and −1082G with −592C (P = 0·005) associated with the disease. These findings support the concept of contribution of IL-10 gene polymorphisms in the pathogenesis of early-onset pre-eclampsia.