Determining reference intervals (RI) is a valuable asset for assessing the health of wildlife species. This is the first study to establish serum biochemical RIs in Siberian weasels. Forty-two healthy free-ranging Siberian weasels were captured live and brought to Seoul Wildlife Center between June 2021 and August 2022. Blood samples from 42 healthy Siberian weasels of both sexes were used to calculate RIs. An automated analyser was used to perform serum biochemistry profiles. The American Society for Veterinary Clinical Pathology recommendations were used to calculate a nonparametric RI with 90% confidence intervals. The RIs of albumin, total protein, globulin, calcium, glucose, blood urea nitrogen, phosphorus, amylase, cholesterol, alanine aminotransferase, total bilirubin, alkaline phosphatase, creatinine, and creatine kinase were determined. The RIs established in this study will serve as a good starting point for analysing serum biochemical data in Siberian weasels.