A cDNA encoding a novel human stearoy-CoA desaturase (dubbed "hSCD5") as well as vectors and cells comprising such polynucleotide are disclosed. Also described are assay methods for determining the ability of small molecules and other chemical agents to increase or decrease he enzymatic activity and/or gene expression level of hSCD5 as well as processes for using such agents to treat, prevent or diagnose a variety of diseases and other conditions.