Deoxynivalenol (DON) is produced by several Fusarium species and may contaminate feeds causing reduced food consumption and utilisation, reduced body weight gain and other unfavourable changes in animals. To verify if its adverse influence involves also hormonal and metabolic changes, the effect of DON on blood insulin, glucagon, leptin and metabolic parameters in growing Wistar rats was studied. Animals were treated subcutaneously with DON in the amount of 1 mg/kg b.w. After 3 days a significant increase in blood insulin, glucose and free fatty acids were observed in these animals in comparison to the control group. DON treatment caused an increment in glycogen depots and a reduction in triglycerides content in the muscle. Studies on isolated adipocytes revealed that DON (20 micromol/l) slightly stimulated basal lipogenesis, whereas insulin-induced lipid synthesis and lipolysis were unchanged. Results obtained after subcutaneous DON administration indicate that its adverse effects in animals may partially result from metabolic disturbances evoked by this mycotoxin.