The present work deals with the survey and identification of different families of Order Hymenoptera during 1998-2004 in Iran. During this work there are 45 species of different families of Order Hymenoptera recorded here as a first time in Iran, including, ninteen species of family Apidae, 3 species of family Andrenidae, 6 species of family Sphecidae and 16 species of family Vespidae. Order Hymenoptera is one of the four great orders of insects (Mason and Tuber,1993). This order fauna of Iran is rather well studied and attracted some workers i.e. Tirgan, 1969, Esmaili & Rastegar, 1974, Ebadi, 1986, Ebadi and Ahmadi, 1986, Ebrahimi, 1993, Ebrahimi, et al, 1995, Talebi et al., 1995, Modarres Awal, 1997 and Karimpour et al, 2002. Samples were collected from different locations of Iran during 1998-2003. All the materials are deposited in Department of Agriculture, Islamic Azad University, Shahr-e-Rey Branch, Tehran — Iran. 1. Family : Apidae The Apidae (Hymenoptera: Apoidea) fauna of Iran is rather well studied and until now 22 spedes are known (Esmaili & Rastegar, 1974, Ebadi, 1986, Talebi ct at, 1995). In the present study, 7 species of 3 genera including, Chelostoma, Nomada, and 5phecodes are reported as the new records. The Bombus spp. (Hymenoptera: Apidae: Apoidea) fauna of Iran is very diverse and at the same time unknown. Until now, only 11 species are known (Esmaili & Rastegar, 1974, Talebi et al., 1995, Modarres Awal, 1997). In the present study, 12 species of 2 subgenus including, Bombus Bombus and Bombus Psithyrus are reported as the new records for Iran. All the materials are deposited in Department of Agriculture, Islamic And University, Shahr-e-Rey Branch, Tehran — Iran.