Leptin receptors (OB-R) are widely distributed in peripheral tissues. However, the RT-PCR data published on the distribution of OB-R are not always consistent. The present study was undertaken in order to test whether the different muscle fiber type profile or the acute nutritional status in which tissue samples were excised from animals may influence OB-R expression. Six 12-week-old male Swiss-Webster mice were killed by decapitation either 1 h after feeding or after a 16-h fast, and the kidneys, testes, brown adipose tissue, gastrocnemius (G), soleus (SOL) and extensor digitorum longus (EDL) muscles were dissected out. In parallel, muscle fibers obtained from other animals were classified on the basis of differences in the staining intensity for myofibrillar adenosinetriphosphatase. The expression of OB-R isoforms was assessed by RT-PCR and ethidium bromide staining. The signal for OB-Ra and OB-Rb was detected in all tissues examined. No differences were observed in samples obtained from either fed or fasted mice. G, SOL and EDL muscles showed the same pattern of OB-R expression. Neither the short-term nutritional changes of the animal as regards to the pre- versus the postprandial-state nor differences in muscle fiber type had any influence on the qualitative expression of the OB-R splice variants a and b in the murine tissues studied. However, quantitative differences cannot be ruled out.