The Przewalski"s horse (Equus ferus przewalskii) became extinct in the wild in the 1960s, but survived as a species due to captive breeding. There have been several initiatives to re-introduce the species in central Asia, but until now only two projects in Mongolia establish free-ranging populations. Data on basic ecology and behavior of the species prior to extinction is largely lacking and a good documentation of the re-introduction process is essential. Between 13 May and 2 September 2003 we documented the time budget-, group synchrony and body score development of a newly released Przewalski"s horse group in the Gobi area of SW Mongolia.Contrary to our expectations, the newly released Przewalski"s horses did not show the expected succession of an exploration-, acclimatization-, and established phase. Grazing activity was very high after the release, decreased to a minimum in July and increased again towards the end of the study in September. Resting activity followed the opposite trend, whereas moving activity was more or less constant over the entire observation period. Behavioral synchronization of the group was high throughout the study period and immigration or emigration of members did not result in a de-synchronization of the group. The body score index never dropped, but rather increased for all group members.Our data suggests that captive bred Przewalski"s horses experience little behavioral and nutritional stress when being released into the desert steppe of the Gobi regions after one year in an adaptation enclosure.