Marine macroalgae are very rich source of phenolic compounds endowed with antioxidant and antimicrobial properties. The aim of this study was to evaluate the bioactivity composition of three selected green, brown and red algae – viz., Halimeda opuntia, Padina pavonica and Halymenia sp., respectively from Jeddah coast in Saudi Arabia. The antimicrobial properties against pathogenic Grame positive, Grame negative bacteria and fungi were tested. In vitro antioxidant activities including 1, 1-Diphenyl -2-picrylhydrazyl (DPPH) radical scavenging, antityrosenase activity  and lipid peroxidation activity were studied. The highest amount of phenolic compound was found in the extract obtained from Padina pavonica this extract also showed good antioxidant activity expressed by its capacity to scavenge superoxide anion and to inhibit lipid peroxidation. Halimeda opuntia, Padina pavonica exhibited good antioxidant activity when compared to Halymenia sp. The maximum antimicrobial activity was shown by the extract of Halimeda opuntia, Padina pavonica  against Klebsiella pneumoniae ATCC 27736 (32mm). The results showed that marine macroalgae exhibited varying degrees of antioxidant and antimicrobial properties.