The products of mammalian LPIN2 and LPIN3 are phosphatidate phosphatase type 1 enzymes, which play an important role in the de novo biosynthesis of triacylglycerol, phosphatidylcholine and phosphatidylethanolamine. In this study, we obtained a 2,985-bp cDNA sequence of porcine LPIN2, which contains a 2,676-bp open reading frame flanked by an 11-bp 5'UTR and a 298-bp 3'UTR, and a 2,843-bp cDNA sequence of porcine LPIN3, which contains a 111-bp 5'UTR, a 2,580-bp open reading frame and a 152-bp 3'UTR. RT-PCR analysis showed that both LPIN2 and LPIN3 mRNA were ubiquitously expressed with a very high level in liver. By using the somatic cell hybrid panel (SCHP) and the radiation hybrid (IMpRH) panel, porcine LPIN2 and LPIN3 were assigned to 6q24-(1/2)q31 and 17(1/2)q21-q23, respectively. One T2193C single nucleotide polymorphism in LPIN2 was identified and was detected by Hin6I PCR-RFLP. Association analysis showed that different genotypes of LPIN2 were associated with back-fat thickness between the 6th and 7th ribs (P < 0.01).