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There has been little success in identifying annual medics (Medicago spp.) able to establish on more arid sites because their growth is limited by the dry summer but also by cold winter. Potential medic species should be tested to improve the forage availability in periods in which herbage production is limited. Hence, cold tolerant autumn-established medics could be a good alternative for pastures in rotation with wheat under cold drylands. The objectives of this study were to compare different species of medics to prove annual medics capacity for winter survival with special emphasis on biomass production under cold rainfed condition in north-west of Iran. Hence, 362 accessions belonging to 16 species of Iranian annual medics were evaluated in two years (2005-2007) under dryland condition. In the first year, about 90% of accessions were killed because of freezing cold, and only 13 cold tolerant accessions with great growth vigor were selected for further studies in the second year. There was a large variation among the selected accessions for plant establishment (5-68%), dry matter (200-2200 kg/ha) and seed productions (20-380 kg/ha) in the second year. Accessions of M rigidula generally showed much better winter survival and biomass production than other medics. We concluded that majority of Iranian medics had poor winter survival; however, M. rigidula accession 51TN1851 seems to be promising for frost tolerance and higher potential for production of forage mass and seed after freezing than other accessions, indicating that it may be suitable for sowing under cold winter conditions predominant in high-dryland areas.