Abstract: Provided is a creatinine assay kit with desirable stability and capable of rapidly eliminating drug interference. The creatinine assay kits include a first reagent R1 and a second reagent R2. The first reagent R1 comprises a first buffer solution, creatinase, sarcosine oxidase, ascorbic acid oxidase, peroxidase or catalase, serum albumin, a first non-ionic surfactant, a first preservative, Trinder's reactant A, laccase, a metal salt, or a combination thereof. The second reagent R2 comprises a second buffer solution, serum albumin, creatininase, a second preservative, Trinder's reactant B, or a combination thereof. The creatinine assay kits eliminate or significantly reduce inaccurate creatinine determination due to negative deviation caused by serum samples containing calcium dobesilate and/or etamsylate.