This study was conducted to evaluate potential interactive effects of supplemental Cr and dietary protein levels in growing pigs. Thirty-six individually penned barrows, 22 to 63 kg, were used in a 2 x 3 factorial arrangement of supplemental Cr (0 or 200 ppb from chromium tripicolinate) and protein level (76, 83, or 90% of lysine requirement). A corn-soybean meal basal diet was designed to supply all mineral and vitamin needs, 90% of the estimated metabolizable energy need, and 76% of the estimated protein need at 70% of ad libitum feed intake. Additional protein to 83 or 90% of the lysine requirement was provided by a soy protein isolate supplement. Growth data were collected for a 50-d period, and pigs were killed at a mean of 63 kg BW. Increasing lysine levels linearly (P < 0.01) increased ADG and liver weight. Lysine level had a quadratic effect on 10th rib backfat thickness (P < 0.05) and cooler shrink (P < 0.01) with the highest responses at the 83% lysine level. Increasing lysine level linearly decreased (P < 0.05) carcass content of ash and lipid and quadratically increased the carcass water content (P < 0.01). Carcass accretion rate showed a linear increase for protein (P < 0.01) and water accretion (P < 0.01). Dry matter composition of the longissimus muscle showed linear increases of ash (P < 0.05) and protein (P < 0.01) and a linear decrease of lipid content (P < 0.01) resulting in a linear increase (P < 0.05) of the protein to lipid ratio based on the increasing lysine levels. Pre-feeding insulin levels were increased (P < 0.05) with increasing level of lysine. One hour post-feeding, a quadratic lysine response for plasma glucose (P < 0.05) was observed with the lowest concentration at 83% lysine. Cr addition increased 10th rib backfat thickness (P < 0.10). There was no Cr x lysine level interaction (P > 0.10) observed for any of the growth or carcass traits. Plasma glucose concentrations pre-feeding were lower for Cr-supplemented pigs (P < 0.01). As expected, increasing protein levels in protein-deficient diets increased protein accretion while decreasing lipid accretion in 22 to 63 kg growing pigs; however, these effects were more clearly seen in the longissimus muscle than in the entire carcass. Supplementation of Cr exerted only minor effects with few Cr x lysine interactions observed in this study.