Reports on the in vivo and in vitro activities of medicinal plants on haemic and humoral trypanosomes showed that several medicinal plants, worldwide, possessed trypanocidal or trypanostatic activity. The choice of specific plants by researchers were based on their trypanocidal claims as documented in ancient pharmacopoeia, knowledge from traditional healers, herdsmen, village elders and feeding habits of large primates. The plants were subjected to various methods of extraction. The choice of extraction method depended largely on the part of the plan to be tested and often, fractionated through thin layer chromatography, infrared spectroscopy, mass spectroscopy, nuclear magnetic resonance spectroscopy to yield bioactive components. This was with a view of elucidating structural components and possible synthesis of new trypanocides. The commonly encountered active principles in the extracts were saponins, terepins, phenolics, flavonoids, tannins, glycosides, anthraquinones, columbins, neolignan, quinines, phlobatanin, resins and alkaloids. These fractions, produced efficacy ether singly or synergistically at dosages (<800 mg kg-1) in vivo, leading to the elimination of parasitaemia, modulating declined red cell indices and the alleviation of clinical signs of trypanosomosis. Most of the extracts however, produced effect in vitro within minutes of application in a graded dose manner. The extracts in most cases produced signs of acute toxicity (in vivo) at dosages (>800 mg kg-1) leading to degenerative changes in vital organs. Signs of cytotoxicity were also encountered in vitro on various cell lines. Therefore, the folkloric medicinal applications of plants for the treatment of trypanosomosis have a pharmacological basis. This may therefore, lead to the synthesis of new, cheap and easily available trypanocides of less toxicity.