The number of old oaks has decreased during the last century and the saproxylic insects associated with the oak are one of the most endangered organism group all over Europe and Turkey. The beetle fauna on old hollow oaks was studied in Sweden and Turkey with window- and pit-fall traps. The most species rich families in the study were Anobidae and Tenebrionidae. The number of saproxylic beetle species was higher at the Turkish sites in comparison with the Swedish. This was most obvious for the families Elateridae, Cleridae, Anobiidae and Tenebrionidae. The overlap among the saproxylic beetle species at the sites in Turkey and Sweden was small. Only 14 (8%) of the 166 species found were shared between the sites in the two countries, most of them being Tenebrionidae. Many of the found beetle species are very rare and can be found on national redlists in many European countries. One good example is the Violet click beetle (Limoniscus violaceus) found at one of the Turkish sites. It is a very rare beetle all over its European range and is listed in Annexe II of the EC Habitat Directive. Three species from the family Staphylinidae were new to science and have been described as Hesperus gozukarai, H. turcicus and H. auricomus.