Based on association and sequencing studies, investigators have postulated muscle segment homeobox 1 (MSX1) as a strong candidate gene involved in the causation of nonsyndromic cleft lip with or without cleft palate (NSCLP). Parent-of-origin effects have been suggested for some NSCLP candidate genes but not for MSX1. The aims of the present study were to test for allele/haplotype associations applying the transmission disequilibrium test (TDT) and the transmission asymmetry test (TAT) to evaluate the possible parent-of-origin effects of MSX1 in Chilean patients with NSCLP. We analyzed five SNPs (rs6446693/c.-425G>T/c.-35G>A/rs3775261/rs12532) located from 6.3 kb upstream to 3' UTR in a sample of 150 unrelated NSCLP case-parent trios. Four haplotypes showed overtransmission from parents to affected progeny, but individual SNPs did not. Two haplotypes presented allele combination C-G-A-G (P = 0.035) and two T-G-C-A (P = 0.044) (SNP order rs6446693/c.-35G>A/rs3775261/rs12532). The rs12532 A allele had a 2.08-fold increase in the risk of NSCLP when inherited from the father (95% CI: 1.10-4.02; P = 0.025), but not from the mother. These results could indicate epigenetic control by imprinting in the role of MSX1 in NSCLP. Different authors have proposed that some genes that play a role in NSCLP depend on parental origin. Our findings and those previously reported by our group show that a variety of factors appears to be involved in the association between MSX1 and NSCLP. The full mechanism of MSX1 in the development of NSCLP has not been fully understood.