Introduction. Cyanide is a very toxic chemical which reacts with the ferric cytochrome oxidase in the mitochondrial system to form a stable complex. This complex inhibits the process of oxidative phosphorylation thereby interrupting aerobic respiration in the organism. Activated charcoal is believed to intercept the ingested cyanide in the gastrointestinal tract before it is absorbed into the blood.Methods. A single dose of 3mg/kg body weight of potassium cyanide was administered orally to the rats in each of the five groups of 6 rats each. After fifteen minutes, all the rats in each group were given a single dose of activated charcoal from different plant biomass materials at a dose of 1g/kg. After 21 days, the rats were humanely sacrificed and the liver, heart and kidney harvested for histopathological assessment using standard histological methods. Results. The histological profiles showed mild to moderate fatty degenerations, inflammations, necrosis and haemorrhages in the heart, kidney and liver tissues of the Wistar rats. Conclusions. The administration of locally-prepared plant biomass adsorbents to the Wistar rats after exposure to cyanide largely mitigated the effects of the cyanide on the histopathological changes in the liver, kidneys and heart of Wistar rats in this study.