General toxicity, antiproliferative, antibacterial and antioxidant activities of Caulerpa peltata J.V.Lamouroux (Caulerpaceae) collected from Oman Sea were investigated. Dried, ground alga was Soxhlet-extracted with hexane, dichloromethane and methanol successively. The methanol extract was subjected to vacuum liquid chromatography (VLC) fractionation on silica gel using a step gradient of different mixture of solvents. A known alkaloid, caulerpin, was subsequently isolated from the fraction eluted by ethyl acatete100%. The antioxidant activity of all extracts was assessed by using the (DPPH) assay. Antiproliferative activity of the all extracts and caulerpin against the cancerous cell line was evaluated using MTT assay. General toxicity of extracts was determined using Brine Shrimp Lethality Assay (BSLA). Based on our results, a weak activity observed for all extracts in MTT assay, while they were toxic toward brine shrimp nauplii comparing to the podophylotoxin. This is the first report on phytochemistry and bioactivity of C. peltata which collected from Oman Sea.