These studies examined the effect in rats of carnitine supplementation on variables of fat metabolism altered by administration of sodium pivalate, a compound which induces a carnitine deficiency. Weanling male rats received 20 mmol/L sodium pivalate or 20 mmol/L sodium bicarbonate in their drinking water for 2 wk. They were food-deprived for 24 h, and to maximize fatty acid oxidation, were cold-stressed for 4 h. In Experiment 1, group 1 received the bicarbonate, group 2 received the pivalate, group 3 received the pivalate and 0.46 mmol L-carnitine in the diet/d, while group 4 received the pivalate and 0.95 mmol L-carnitine in the diet/d. In Experiment 2, group 1 received unsupplemented drinking water, group 2 received the bicarbonate, group 3 received the pivalate, and group 4 received the pivalate and 0.95 mmol L-carnitine in the diet/d. Pivalate-treated rats given the low carnitine diet had plasma and liver triglyceride levels (Experiment 1), plasma β-hydroxybutyrate concentrations (Experiments 1 and 2) and urinary dicarboxylic acid excretion (Experiment 2) significantly greater than those of controls (P < 0.05). The reduced tissue carnitine concentrations, starvation ketosis and lipid accumulation in the liver are findings also reported for human secondary carnitine deficiency due to organic acidurias. Supplementing the diet with L-carnitine at the level of 0.95 mmol/d significantly raised plasma and tissue carnitine concentrations and reduced the plasma β-hydroxybutyrate and liver triglyceride concentrations to levels not significantly different than control values. Carnitine supplementation ameliorates the degree of liver lipid accumulation and exaggerated starvation ketosis induced by pivalate.