Random amplified polymorphic DNA (RAPD) markers were used to estimate genetic relationships between two seasonal immigrant forms (namely fall-run and spring-run) of Caspian trout Salmo trutta caspius. In this regard, 62 fin tissue samples were collected from southern parts of the Caspian Sea basin and examined with 16 oligodecamer primers to asses their genetic diversity as well as probable specific population bands. The total number of RAPD bands produced in spring and fall-run were 162 bands, of which 69 and 53 bands were polymorphic for each population. Nei's genetic identity and genetic distance between spring-run and fall-run populations were 0.9858 and 0.01430, respectively. The RAPD based data revealed that the two migratory forms of Caspian salmon were categorized in conspecific value.