The Suppressor of Cytokine Signalling-2 (SOCS2) is the main negative regulator of somatic growth through the mediation of growth hormone signalling (GH/IGF-1). Knock-out and naturally mutant mice have high growth phenotypes. We have mapped the porcine SOCS2 gene to chromosome 5q, located closely to a reported QTL for food conversion ratio (Lee et al., 2003). Here we report five single nucleotide polymorphisms identified by sequencing of the promoter region and exon 1. One PCR-RFLP assay was designed for genotyping the polymorphism at position 1667(A/G). Association analyses were performed in an Australian mapping resource pedigree (PRDC-US43) for a number of traits (feed conversion ratio, backfat, IGF-1 level and growth traits) and showed significant effects on average daily gain on test (ADG2) (p<0.01) and marginal association with feed conversion ratio (FCR) (p<0.08).