Carrageenan, is one of the food additives and is used as a firming agent in healthcare products like toothpaste. The aim of this study was to analyze the chronic toxic effects of kappa carregeenan  (k- CGN) on the thyroid gland and pancreas in experimental rats and to evaluate the possible ameliorative effect of Diacerein. This study was done on fifty adult male albino rats. The rats were divided into 5 groups (10 rats in each group) in the form of; control group, Carboxymethylcellulose group (1.2ml/Kg), Diacerein group (30mg/Kg), Carrageenan group (50mg/Kg), and Diacerein( 30mg/kg) + Carrageenan (50mg/kg) combination group All drugs were given orally for 3 months. By the end of the 3^rd month, thyroid and pancreatic functions were assessed by biochemical, histological, and immunohistochemical investigations. Rats group that were given Carrageenan alone had significantly higher thyroid MDA (malondialdehyde), lower thyroid GSH  (reduced glutathione)  and serum T4 levels than the untreated control rats group, but co- treatment of Carrageenan- exposed rats with diacerein had an ameliorative effect on the previous results. Light microscopic examinations of thyroid gland sections revealed that Carrageenan caused significant marked hypothyroid changes, and significant mild hypothyroid changes were observed in the rats which received Carrageenan + diacerein combination. Immunohistochemical studies of thyroid gland showed that carrageenan caused significant marked expression of PCNA and significant mild expression was observed in rats received combination of diacerein + carrageenan. Regarding pancreas, this study revealed no significant statistical changes in serum amylase level, MDA and GSH levels. Also, there were not any significant pathological changes of pancreatic tissues of carrageenan group. Thus, it appears that carrageenan can induce oxidative damage in the thyroid gland of rats and diacerein has an ameliorative effect against this damage.