The concentrations of metals were measured in macroalgae species seasonally at eight coastal stations along the eastern Aegean coast. Sediment and seawater samples were also collected to detect their metal contents in order to gain more information on the environmental conditions of the area and possible bioaccumulation patterns. The aim of this study is, to gather more information on the use of selected species as cosmopolitan biomonitors for the eastern Aegean; to provide information on the marine environmental quality by the use of macroalgae and to determine which algae species are suitable as biomonitoring species for the study area. The relative abundance of metals in macroalgae decreases in the order: Fe–Zn–Cu–Cr–Cd–Hg–Pb and seawater: Fe–Zn–Pb–Cu–Cr–Cd–Hg. In sediment the distribution order from higher to lower was Fe–Cr–Zn–Pb–Cu–Hg–Cd. The brown algae Cystoseira sp., the green algae Ulva sp. and Enteromorpha sp. possess high potential as cosmopolitan biomonitors for trace metals in the Aegean Sea.