The crude n-hexane, carbon tetrachloride, chloroform,ethanol extracts and water extract of leaves of Calotropis gugantea were evaluated for antimicrobial and cytotoxic activity. The antimicrobial screening was done against 16 microorganisms including gram-positive, gramnegative and fungi by the disc diffusion method. The carbon tetrachloride fraction and ethanolic fraction showed little antimicrobial activity with average zone of inhibition 9.5 mm and 8.4 mm respectively at a concentration of 400μg/disc. The antimicrobial activities were compared with standard antimicrobial doxycycline (30μg/ disc) which showed an average zone of inhibition of 40 mm. In the cytotoxic assay the extracts were tested for Brine Shrimp Lethality Bioassay using Brine shrimp nauplii. The administration of the crude extract induced significant cytotoxic activity where the LC50 and LC90 of crude extract were 2.08 μg/ml and 122.35μg/ml respectively after 24 hours.
