1. Muscle injury (rhabdomyolysis) is one of the causes of acute renal failure (ARF). Iron, free radicals and nitric oxide (NO) play a critical role in the pathogenesis of glycerol-induced myoglobinuric ARF. L-Carnitine is an anti-oxidant and prevents the accumulation of end-products of lipid peroxidation. Therefore, the aim of the present study was to investigate the effects of L-carnitine on myoglobinuric ARF induced by intramuscular (i.m.) hypertonic glycerol injection. 2. Sprague-Dawley rats were divided into three groups. Rats in group 1 (n = 8) were given saline, whereas those in groups 2 (n = 10) and 3 (n = 10) were injected with glycerol (10 mL/kg, i.m.). Concomitant with and 24 h after glycerol injection, L-carnitine (200 mg/kg, i.p.) was administered to group 3 rats. Forty-eight hours after glycerol injection, blood samples and kidney tissues were taken from anaesthetised rats. 3. Plasma creatine kinase (CK) activity, urea, creatinine and NO levels, as well as kidney tissue superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) enzyme activity and malondialdehyde (MDA) and glutathione (GSH) levels, were determined. In the kidney tissue, histopathological changes and iron accumulation in the tubular epithelium were also investigated. 4. Glycerol treatment caused severe ARF: a marked renal oxidative stress, significantly increased CK activity, urea and creatinine levels and decreased plasma NO levels. Histopathological findings in group 2 rats confirmed that there was renal impairment by cast formation and tubular necrosis and a marked increase in iron accumulation in the tubular epithelium. All these factors were significantly improved by L-carnitine supplementation. 5. These results may indicate that L-carnitine treatment protects against functional, biochemical and morphological damage and iron accumulation in glycerol-induced myoglobinuric ARF in rats. In this model, the protective effect of L-carnitine treatment may provide a new insight into the treatment of rhabdomyolysis-related ARF.