There is an increasing demand for natural antioxidant molecules to replace the synthetic additives currently used in the food industry. Therefore, in this study, the total phenolic contents, total antioxidant capacities (lipid-soluble and water-soluble), total protein contents, vitamin E contents and vitamin C contents of Ulva rigida C. Agardh, Codium tomentosum Stackhouse, Gracilaria gracilis (Stackhouse) M. Steentoft, L.M. Irvine et W.F. Farnham and Sphaerococcus coronopifolius Stackhouse were determined. According to our data, among the algae studied, the highest levels of bioactive components were found in U rigida, followed by C. tomentosum, G. gracilis and S. coronopifolius. In particular, U. rigida and C. tomentosum showed the highest values for all of the parameters studied. Therefore, U rigida and C. tomentosum could be considered as species possessing significant natural antioxidant molecules which might be useful for the food industry.