Polymorphisms MC4R c.1426A>G (p.Asp298Asn) and LEPR c.2002C>T (p.Leu663Phe) have been associated in pigs with feed intake, growth and fatness. Our aims were to analyze how these polymorphisms influence production and quality traits in Duroc × Iberian crossbred pigs, and moreover evaluate how the effects of gender and Duroc line were affecting these traits. Significant effects of gender, Duroc sire line and LEPR c.2002C>T mutation, were detected on the main traits. LEPR c.2002T allele increased body weight (2.5 ± 0.7 kg), backfat thickness (1.5 ± 0.4 mm), loin intramuscular fat (0.7 ± 0.2 %), and lightness (1.0 ± 0.3); however it was decreasing premium cuts yield (− 0.9 ± 0.2%). Allele c.2002T increased SFA (0.60 ± 0.12 %), and decreased MUFA (− 0.35 ± 0.12%) and PUFA (− 0.25 ± 0.06%). No significant effects of MC4R c.1426A>G SNP were identified. A genetic test based on the LEPR c.2002C>T SNP may be useful to select Duroc sires to reduce undesirable heterogeneity of carcasses and premium cuts of crossbred animals.