Levels of expression of the leptin receptor (OB-R) splice variants have been studied in human omental white and perirenal brown adipose tissues by reverse transcription-PCR. The level of mRNA expression of the full length form (OB-Rb) was approximately 15% of that of the sum of all splice variants in white or brown adipose tissue. In an attempt to quantify the gene expression of OB-Rb in human white adipose tissue, a quantitative competitive PCR technique was developed, using oligonucleotide primers designed for OB-Rb and an internal standard for a "MIMIC" competition strategy. The levels of expression of OB-Rb mRNA in the omental fat of lean and obese patients were compared and no difference could be observed between the two groups. The quantitative RT-PCR technique allows for a fast and accurate measurement of the expression of the OB-Rb mRNA in small tissue samples.