Hibiscus sabdariffa had been reported to have a broad range of therapeutic effects. The effects of oral administration of Hibiscus sabdariffa aqueous extract on some biochemical parameters were studied in wistar albino rats. A total of twenty five (25) male albino rats were grouped randomly into groups. Group A (control), Group B (0.6g/100ml of water of HS extract) Group C (1.2g/100ml HS extract), Group D (1.8g/100ml HS extract) and Group E (1.8g/100ml + vitamin C) and treatment period was 28 days. The results indicate an increase activity of liver function enzymes; alkaline phosphatase (ALP), alanine transaminase (ALT), aspartate transaminase (AST). This increase was statistically significant (p<0.05) when compared with Group A (control) in a dose dependent manner.No significant difference was observed in total and direct bilirubin in all the groups. Similarly for renal indices, bicarbonate (Hco3), urea and creatinine in all the groups, but a significant increase (p<0.05) in sodium (Na+) and potassium (K+) and chloride were noted in comparison to the control.It is of note that there was no significant difference between results of Group E and the control (Group A). However, this study suggests that long term administration of the extract may indeed be toxic to liver and kidney especially at high doses.