It has been reported that some amino acids can function as signaling molecules to regulate skeletal muscle growth in mammals. This study was conducted to identify those genes that may be regulated by amino acid lysine and responsible for muscle growth and meat quality of pigs. Nine crossbred barrows (94.4 ± 6.7 kg BW) were randomly allotted to 3 dietary treatments (3 pigs/treatment). Three corn and soybean-meal based diets were formulated to meet the NRC (2012) requirements for nutrients except for lysine, whose concentrations were 0.43, 0.71, and 0.98% for Diets 1 (lysine deficient), 2 (lysine adequate), and 3 (lysine excess), respectively. After 5 weeks on trial, pigs were killed and muscle samples collected from longissimus dorsi (between the 10th and 12th ribs). Total RNA was extracted from 50 mg of each sample using a TRIzol reagent. Porcine Gene 1.0 ST Array (Affymetrix, Inc.) was used to quantify the expression levels of 19,211 genes. Raw microarray data were normalized with gcRMA algorithm and analyzed with ANOVA using Partek Genomics Suite (Partek Inc.). A total of 674 transcripts were differentially expressed (P < 0.05); 60 out of 131 transcripts (P < 0.01) belong to 59 genes and 71 were unannotated. GO Enrichment analysis of this 59-gene set identified 11 genes in 5 categories of molecular functions: binding, catalytic activity, transcription regulator activity, transporter activity, and molecular transducer activity. Interestingly, 4 genes are associated with lipid metabolism: PSPH: lipid binding and key enzyme for serine (precursor of phospholipids and glycolipids) synthesis; CFD: stimulating glucose transport for triglyceride accumulation and inhibiting lipolysis; ME1: associated with backfat thickness and meat quality; SCD: playing a key role in intramuscular fat formation. It appears that lysine can regulate the expression of multiple genes, and at least 4 genes are related to lipid metabolism. Further studies are needed to elucidate the association of dietary lysine level with the expression levels of these genes and the gene network for lipid metabolism. (Supported by USDA Hatch/Multistate Project 233803)