Collection and identification of insect fauna in agricultural areas is regarded as a fundamental research in plant protection and agricultural entomology. In this study, Heteroptera fauna of alfalfa fields in Azarshahr region of Azarbayejan e sharqi province of Iran was studied by means of sweep net and aspirator during 2003–2005. A total of 13 species belonging to 6 families (Alydidae, Lygaeidae, Nabidae, Miridae, Rhopalidae, Pentatomidae) of Heteroptera were collected and identified. The species Nabis pseudoferus, and Nabis capsiformis were identified as predators and other species were phytophagous. Miridae had the most frequency among families and Lygus pratensis, Lygus regulipennis, Adelphocoris Lineolatus, and stenodema turanicam had the most frequent species. Nabis capsiformis was reported for first time from Azarbayejan e sharqi province. New species for Azarshahr region and Azarbayejan e sharqi province marked by one (*) and tow (**) asterisks respectively. Collected families and species were as follow:Alydidae:                                               Nabidae:*Comptopus lateralis                              *Nabis pseudoferusLygaeidae:                                             *,**Nabis capsiformis*Emblethis spp                                       Pentatomidae:Miridae:                                                 *Carpocoris coreanus*Exolygus pratensis                                *Carpocoris fuscispinus*Exolygus regulipennis                            *Dolycoris baccarum*Adelphocoris lineolatus                          Rhopalidae:*Stenodema turanicum                           *Corizus hyoscyami*Deraeocoris pallens