Transforming growth factor β1 plays a significant role in pregnancy outcome. We investigated the association of TGFB1 exon 1 (rs1800471, rs1800470) and promoter region (rs1800469, rs1800468) polymorphisms with recurrent pregnancy loss (RPL) in 675 Tunisian women: 304 women with a history of three consecutive pregnancy losses of unknown etiology with the same partner and 371 age-matched multiparous control women. TGFB1 genotyping was done by TaqMan assays. Higher minor allele frequency for rs1800471 (P< 0.001), but not for rs1800470, rs1800469 or rs1800468 was found in RPL cases compared with controls. A significant difference in the distribution of rs1800471 genotypes was seen between the RPL cases and control women, irrespective of the genetic model used. Increased RPL risk was seen with rs1800471 allele C in the heterozygous state and to a greater degree in the homozygous state, thus establishing a dose-dependent effect. Haploview analysis revealed differential linkage disequilibrium between the TGFB1 single-nucleotide polymorphisms analyzed. TGFB1 haplotype analysis identified eight common haplotypes (rs1800471/rs1800470/rs1800469/rs1800468) with three (GTTG, Pc = 0.02; CCTG, Pc = 0.02 and CTCG, Pc = 0.02) positively associated with RPL and one (GCCG, Pc = 0.009) negatively associated with RPL. This study provides the first evidence that the TGFB1 genotype may influence RPL.