¹Department of Pharmacy, Medical Faculty, Universitas Tanjungpura, Pontianak, Indonesia DOI : 10.29228/jrp.805 Cincalok is a fermented shrimp from West Kalimantan, Indonesia, which has many beneficial compounds such as omega-3 and astaxanthin. The LD50 of the cincalok oil was more than 5000 mg/ Kg BW (practically non-toxic), so there is an opportunity that cincalok can develop into a supplement. However, single and repeated doses may have different toxic potential. This study aimed to observe the sub-chronic toxicity of cincalok oil in Wistar strain rats (Rattus norvegicus L.) after 28 days of repeat doses in oral administration based on OECD 407 test guidelines. Thirty of the male and female Wistar strain rats were divided into six groups respectively that consisted of one control group of Virgin Coconut Oil (VCO) administration, three dosing groups of cincalok oil administration with dose variation of 100, 400, and 1000 mg/Kg BW, and two satellite groups of 1000 mg/Kg BW dose of cincalok oil administration and VCO control administration. The biochemistry and histopathological investigation was performed. The results showed the biochemical profiles of cincalok oil has no effect on LDL, urea, creatinine, serum glutamate oxaloacetate transaminase, and serum glutamate pyruvate transaminase blood profiles. While on total cholesterol, triglycerides, and HDL profiles, it has reversible effect. Histopathological investigation showed minimal fat degeneration with little congestion and necrosis in the liver, hypertrophy, and hypercholesterolemia in the heart, hydropic degeneration in the kidney, and no disturbance was found in the lung and spleen. Based on biochemical and histopathological result showed that cincalok had no toxic effect and potential to be developed as drug. Keywords : Blood biochemistry; Histopathology; Cincalok oil; Sub-chronic toxicity for 28 days; Wistar rats