LIM domain proteins are important regulators of the growth, determination and differentiation of cells. Four-and-a-half LIM-only protein 3 (FHL3) is a type of LIM-only protein that contains four tandemly repeated LIM motifs with an N-terminal single zinc finger (half LIM motif). In this study, we have determined the complete coding sequence of pig FHL3 which encodes a 280 amino acid protein. The coding region of the pig FHL3 gene is organized in five exons and spans an approximately 2.1-kb genomic region. Comparative sequencing of six pig breeds revealed three single nucleotide polymorphisms (SNPs) within exon 2 of which an A-->G substitution at position 313 changes a codon for arginine into a codon for glycine. The substitution was situated within a PstI recognition site and developed as a PCR-RFLP marker for further use in population variation investigations and association analysis. The A/G polymorphism was segregating only in Landrace pigs. Association studies of the FHL3 polymorphism with carcass traits provided preliminary evidence that the PstI PCR-restriction fragment length polymorphism (RFLP) genotype may be associated with variation in several carcass traits of interest for pig breeding. Further investigations in more Landrace pigs are needed to confirm this.