Ricinus cmmunis L. (Castor oil plant) is an important medicinal plant belonging to family Euphorbiaceae. Its phytochemistry, biological and pharmacological activities, and ethnomedicinal uses have been reviewed in the present study. The reported chemical constituents showed the presence of flavonoids, phenolic compounds, fatty acids, amino acids, terpenoids, phytosterol etc. The compounds have been reported to exhibit anticonceptive, antidiabetic, antifertility, anti-inflammatory, antimicrobial, antioxidant, hepatoprotective, insecticidal and wound-healing activities. They also showed free radical scavenging and Hg scavenging activities, and repellent properties. Various parts of R. communis have been widely used in traditional medicine such as abdominal disorders, arthritis, backache, muscle aches, bilharziasis, chronic backache and sciatica, chronic headache, constipation, expulsion of placenta, gallbladder pain, period pain, menstrual cramps, rheumatism, sleeplessness, and insomnia. Castor oil plant has also revealed toxic effects due to the presence of ricin (protein) and ricinine (alkaloid). Comparatively, ricin is more toxic. But still there is need of more research to be conducted with reference to its medicinal importance (particularly exploring of medicinal recipes) and active compounds responsible for various activities.