Although the different species of Dunaliella are nearly identified but some species in culture collection are still misnamed. In this work the primary and tertiary semantides were analyzed for the identification of four species of Dunaliella. The results of tertiary semantides including protein profile and isozymes pattern revealed that there is no species relation between the four species specially between D. salina and D. bardawil. The results of PCR-RFLP-DNA banding pattern strengthened those obtained from the isozymes and protein profile pattern and proved that D. bardawil is neither a synonymous species of D. salina nor of D. parva but D. bardawil should be regarded as separate species. This basic molecular biology technique recommended to be used in ascertaining the genetic relatedness and diversity of taxa.