Opuntia elatior Mill. (Cactaceae) is a xerophytic perennial bushy shrub, 1-3 m tall, widely distributed throughout India. It is commonly known as Prickly pear and Slipper Thorn. Almost all parts of the plant are used in traditional medicinal system for curing various diseases. Its fruits, roots and leaves possess anticonvulsant, antidepressant, antibacterial, anti-inflammatory, hypolipidemic and antipyretic activity. The phylloclade’s (cladodes) are considered as very tasty, stomachic and cure inflammations, tumors and pains. Ripe fruits of the plant contain red pigment i.e. betanin which is betacyanin pigment. The hydro-alcoholic extract of Opuntia elatior fruits was studied for its in-vitro antioxidant and cytotoxic activity by using DPPH radical scavenging and MTT assay on K-562 cell line (Human chronic myelocytic leukemia). The total phenolic, flavonoid, flavonone and betanin pigment content were also estimated by spectrophotometric methods. It showed the significant antioxidant activity with IC50 value 88.16µg/ml and potent cytotoxic action against K-562 cell line with IC50 value of 25 µM/ml compared with the standard.