Effect of drifting on amino acids profile and mineral content in attached and drift marine algae: Dictyota dichotoma, Sargassum vulgare and Cystoseira spinosa (phaeophyta) was investigated as well as, their antioxidant activity in relation to their total phenolic content. All algae tested displayed similar amino acid patterns, with predominance of aspartic and glutamic acids in their tissues. Total phenolic contents varied from a minimum of 0.22 mg g^-1dw in drift Cystoseira samples, to a maximum of 0.93 mg g^-1dw in attached Dictyota samples. The results revealed that drifting negatively affect the phenol content of studied species. The extract of attached and drift D. dichotoma found to have the most potent antioxidant activity (45.38 and 33.61%), respectively. Cu and Na were presented in low values, especially in Dictyota dichotoma, while Fe and K were the most abundant elements in all algae analyzed. All micro and macro elements values were negatively affected by drifting, except those values of K, Ca and Mg in Cystoseira samples.