The work builds on the results of microarray analysis and deals with the analysis of differential expression of muscle tissue in pigs. Using quantitative real-time RT-PCR the expression of 12 genes (ANXA1, ANXA2, BTG2, CSRP2, DAB2, EMP3, HBEGF, IL18, PRKAR1A, SGCD, SORT1, TGFB2) involved in the development and growth of muscle in pigs was validated. Differential expression of two muscles (m. longissimus lumborum et thoracis and m. biceps femoris) between Wild Boar and Czech Large White, which differ significantly in growth, was determined. All genes were overexpressed in Czech Large White. In order to resequencing and polymorphism detection, IL18 gene, encoding proinflammatory cytokine was selected. IL18 was previously associated with lipid metabolism, insulin-resistance and skeletal muscle function. In fragments covering exon 2, 4 and 5 a total of 40 polymorphisms were found. PCR-RFLP methodology was designed for two polymorphisms: ENSSSCG00000015037:g.11237G>A in exon 2 (MspI) and g.19480G>A in intron 5--6 (VspI) and the association analysis with the performance and meat quality traits in selected populations in pigs (n = 344 and 669) was evaluated. IL18 was associated with growth, muscle formation, fat deposition and meat quality traits. IL18 could be potentially useful for MAS in pigs.