During the period 1994-2002, Copidosoma boucheanum (Chalcidoidea: Encyrtidae), Chrysocharis pentheus, Closterocerus ruforum, Cirrospilus vittatus, Colpoclypeus florus, Dahlbominus fuscipennis, Diglyphus minoeus, Diglyphus crassinervis, Eulophus larvarum, Pediobius metallicus, Quadrastichus sp., Sympiesis sericeicornis (Chalcidoidea: Eulophidae), and Halticoptera poreia (Chalcidoidea: Pteromalidae) were established as parasitoids of different forest insect pests in Bulgaria. C. boucheanum, C. ruforum and H. poreia are new records for Bulgarian fauna. Two parasitoid-host relationships (H. poreia - Paraphytomiza populi and S. sericeicornis - Glyptapanteles liparidis on Clostera anastomosis) were established for first time in this study. C. ruforum was an egg parasitoid, and the remaining species - larval and pupal parasitoids. Twelve species are primary parasitoids, and S. sericeicornis is a hyperparasitoid of the braconid G. liparidis. The primary parasitoids reduced population density of the hosts with 2.1-33.3% Insecta (Arthropoda): [Host; New record]. Paraphytomyza populi (Agromyzidae): [Host; New record]. Chalcidoidea (Terebrantia): [Parasite; New record]. Copidosoma boucheanum (Encyrtidae): [New record]. Copidosoma ruforum (Encyrtidae): [New record]. Sympiesis sericeicornis (Eulophidae): [Parasite; New record]. Halticoptera poreia (Pteromalidae): [Parasite; New record]. Glyptapanteles liparidis (Braconidae): [Host; New record]. none2004