Introduction - Iranian plateau with its outstanding geographical and climatic conditions has been considered a key region in the study of Pleistocene human societies. So far numerous Paleolithic sites have been discovered throughout Iran; however, our knowledge concerning the Upper Paleolithic occupations was limited to Zagros region. The Upper Paleolithic occupations of northern Alborz Mountains and southern Caspian Sea has been remained unknown. In this context, the discovery of the open air site of Garmrud 2 by the French-Iranian Paleoanthropological Project (FIPP) in 2005 was a major breakthrough in case of filling the mentioned gaps between older Paleolithic materials and those of Mesolithic from the southeastern of the Caspian Sea (e.g., Komishan, Huto, Kamarband, Al Tepe). Materilas and Methods The southeastern of the Caspian Sea is a strategic region for those interested in prehistoric human movements and dispersions. This regain is one of the proposed migratory corridors for prehistoric societies. The studied area is located between two geographical barriers: in the north is located the Caspian Sea and in the south of the Alborz Mountains. Between these barriers, there are Mazandaran and Gilan Plains with high rate of precipitations and numerous permanent and seasonal rivers. Such geographical conditions have made these plains so fertile, and attracted human societies since prehistoric times. Even today this area represents one of the densest human populations in Iran. Results and Discussion - First, it was Carlton S. Coon who conducted several field missions at the southeastern of the Caspian Sea leading to the discovery and excavation of two famous caves of Huto and Kamarband (Coon, 1951, 1952). Later Charles McBurney from University of Cambridge followed Coon’s footsteps and excavated sites of Key-Aram I and Al Tepe (Ali Tepe). In most recent years, another Mesolithic site (Komishan Cave) was excavated in the region (Vahdati Nasab et al., 2011). The astonishing point conserving these sites chronology is the fact that none belonged to the Upper Paleolithic (Key-Aram I consist of Middle Paleolithic and Mousterian materials and the rest was assigned to the Mesolithic period). For some reasons it was believed that the Upper Paleolithic is the lost period in the north and northeastern of Alborz. Similar scenarios have been observed in Turkmenistan and Tajikistan, which provoked some researchers to claim due to some climatic obstacles of these geographical regions were abandoned during the Upper Paleolithic period. That is why the discovery of a well dated site of Garm Rud 2 could shed light on some of the key aspects of this enigma. This site, which is situated at the river cut of Garm Rud River nearby the Baliran village in Amol, has witnessed three consecutive excavations producing immense amount of data in form of lithic, bones, and shells. The absolute calibrated dating of 33878±3300 plus dominance of balde/ bladelet knapping technologies leave no room for any doubt to associate Garm Rud 2 with the Upper Paleolithic period. Evidence of fauna remains in close association with lithic materials indicates that Garm Rud 2 was a butchering station, which was occupied for a brief time period. Lithic assemblages of the first excavation season were the subject of this research. In this regard, only 2.6% of the assemblage belongs to core/core fragments. Such fact plus low quantity of cortical pieces indicate that the initial preparation stages were taken place somewhere outside of the site. Bladelets are in largest quantity followed by flakes with no secondary edge work and blades. Considerable number of flake debitage implies that they have been byproducts of bladelet/blade production sequences. Conclusion - In case of comparative studies, Garm Rud 2 represents close affinities with the two Upper Paleolithic open air sites of Sefid-Ab and Delazian both located at the southern hills of Alborz Mountains. At the same time it deviates significantly from the Upper Paleolithic cave site of Yafteh in Zagros. Prior to apply any stylistic explanations, the geomorphological formations of these sites must be taken into considerations. In addition, the site formation and usage of the sites must be taken into account. Yafteh is a Karstic cave in Zagros, which based on its strategic location and abundance number of lithic/fauna materials had been a base camp during the beginning of the Upper Paleolithic period. On the other hand, as it was mentioned earlier Garm Rud 2 was a butchering station with short occupation period; therefore, comparing lithic techno-typologies of Yafteh and Garm Rud 2 might not provide comprehensive results. Up until present Garm Rud 2 is the only well dated Upper Paleolithic settlement at the north of Iranian plateau.