Arka, an important medicinal plant of Ayurveda has been equated with three botanical sources namely, Calotropis procera, Calotropis gigantea and Calotropis acia. Various parts of the drug Arka have been highlighted for their therapeutic applications both internally and externally. Being a plant enlisted under poisonous group of drugs, the internal application of Arka is not in practice in random. Single hand information on the internal applications of Arka in various formulations from classical literature is not available. A critical review was made from 60 texts dealing with treatise, compendia and books of Rasashastra. Result shows 547 internal applications in almost 48 texts. Latex and root are the major parts used. The latex of Arka has been profoundlyused in 115 formulations being indicated for Jvara (pyrexia) followed by Kushtha (Skin disorders) etc. This vast data of therapeutic claims of a poisonous plant infer the need to explore the plant for these medical conditions.