The aim of this study was to use association analysis to identify genetic variants in the swine PROP1 gene that influence reproductive traits. Two novel polymorphisms were detected in the 3′-untranslated region (UTR) (NM_001001263:c.1257 G>T, c.1273 A>G) of PROP1. We then genotyped 39 Landrace purebred and 277 Landrace × Large White crossbred sows and conducted an association analysis using 10 reproductive traits. In the Landrace purebred population, the G allele of the SNP c.1257 G>T and the G allele of the SNP c.1273 A>G were associated with greater number of pigs born alive (PBA) (P<0.01 and P<0.05, respectively). The c.1273 A>G heterozygotes had a significantly greater mean total pigs born (TPB) (P<0.05) and PBA (P<0.01) among the crossbred sows. These results indicated that these PROP1 SNPs associated with some of reproductive traits.