The human growth hormone receptor (GHR) mediates the effects of growth hormone (GH1), starting a signalling cascade that is involved in the regulation of proliferation, differentiation and apoptosis. Recently, an isoform of the GHR gene lacking exon 3 (GHRd3) was associated with accelerated responsiveness to growth hormone. In this study, we investigated the association of the GHRd3 polymorphism with breast cancer risk and performed a haplotype analysis with 3 additional single nucleotide polymorphisms (SNPs) (Gly186Gly, Cys440Phe and Ile544Leu) in the GHR coding region in a Polish cohort. We did not observe any effect of the 4 polymorphisms on breast cancer risk. Neither did the 3 most common haplotypes influence breast cancer risk. However, a rare haplotype (dGGC), containing the GHRd3 allele, was associated with a decreased breast cancer risk (OR 0.30, 95% CI 0.11-0.80).