Abstract: In this study, bioecological characteristics of the Mediterranean mussel, Mytilus galloprovincialis (Lamarck, 1819) and the Horse mussel, Modiolus barbatus (Linnaeus, 1758) occurring in Dardanelles were studied between May 2002 and March 2003. Physico-chemical characteristics of sea water were also evaluated. The samples were collected by free diving and using R/V BILIM-I and R/V Uni-Dardanos. A total of 1282 Mytilus galloprovincialis and 280 of Modiolus barbatus were used in experiments.