Abstract. The objective of this study was to investigate physicochemical characteristics and collagen solubility of pigs fed with dietary ractopamine (RAC) during finishing period. Thirty of three-way crossbred pigs (Large White × Landrace × Duroc) with an initial bodyweight (BW) of 18.0 ± 0.5 kg were randomly assigned to one to three dietary RAC inclusions (0, 20, or 40 mg/kg) fed during finishing period (60-100 kg BW). Each group consisted of five gilts and five barrows. After 109 day of raising period, all pigs were slaughtered at the average weight of 100 kg. Longissimus dorsi muscle (LD) was taken from each carcass after overnight chill and analyzed for physical characteristics, chemical composition, and collagen solubility. The LD from pigs fed 40 mg/kg of RAC had lower a* value (p < 0.01) than others. Pigs fed with 40 mg/kg of RAC had higher Warner-Bratzler shear force (p < 0.05) than pigs fed without RAC. Pigs fed with dietary RAC had lower glycogen content than control (p < 0.01). While other chemical compositions and collagen solubility of LD were not affected by dietary RAC (p > 0.05). Gilts had larger muscle fibers (p < 0.01), lower glycogen content (p < 0.05), higher content of insoluble collagen (p < 0.05), total collagen (p = 0.054), and collagen solubility (p = 0.054) than barrows.