The present invention discloses pyrido[2,3-B]pyrazin-3(4h)-ones for use as inhibitors of stearoyl-CoA desaturase. The compounds are useful in treating and/or preventing various human diseases, mediated by stearoyl-CoA desaturase (SCD) enzymes, especially diseases related to abnormal lipid levels, cardiovascular disease, diabetes, obesity, oily skin conditions, metabolic syndrome, and the like.