Hibiscus sabdariffa Linn has been reported to have a broad range of therapeutic effects. Subchronic effects of calyces aqueous extracts of H. Sabdariffa were studied in albino rats. Twenty four (24) albino rats were randomly divided into six (6) groups of four rats each. Group A, was fed with growers mesh and distilled water as control. Groups B to F were administered orally with the aqueous extract at 1, 2, 3, 4 and 5g /kg body weight respectively and the treatment period was 28 days. A decreased in weights of the animals were observed at all dose levels. The activities of liver maker enzymes (alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase) and direct bilirubin increased significantly (p<0.05) in comparison to the control. However, non significant (p>0.05) increase in concentrations of total protein and albumin were observed in comparison to the control. The renal indices, urea, uric acid and creatinine in the treated groups were significantly increased compared to the control but a significant decrease (p<0.001) in sodium (Na + ) and potassium (K + ) were noted in comparison to the control. Although the results revealed a dose dependant variation in the liver and renal indices, nonetheless these results suggest that high dose of calyx extracts of H.sabdariffa may be toxic to liver and kidney.