Indonesia is a country with the largest Muslim population in the world, which is very concerned about halal food. The most problem that’s very concerning nowadays was that food products were contaminated by unclean meat, such as rat meat. The purpose of this study was to authenticate rat fat using Gas Chromatography-Mass Spectrophotometry (GC-MS) combined with chemometrics. In this study, rat fat were heated in oven at 90 °C – 100 °C for approximately one hour until the oil came out. After that, the derivatization process was carried out to convert fat into methyl ester compounds using NaOCH3 and BF3. Methyl ester compound than injected into the GCMS instrument system. In addition to rat fat, other fat extraction were carried out, such as pigs, cows, chickens, wild boars, dogs, and goats. The combination of chemometrics Principal Component Analysis (PCA) was used to classify rat fat with other animal fat. Based on the results of the study showed that fatty acids in rats using GCMS produced 6 types of fatty acids, namely: myristat (0.15 ±0.09%), palmitoleate (0.73 ±0.54%), palmitate (19.08 ±3.54%), linoleate (30.14 ±16.90%), oleate (40.48 ±2.74%), and stearate (2.55 ±0.01%). Total content of rat fatty acids was 93.13%, with unsaturated fatty acids 71.35% and saturated fatty acids 21.78%. Chemometrics PCA from rat fat can be grouped with other animal fats.