The results of an ethnobotanical study on the use of wild and cultivated plants in middle, west and south Bosnia and Herzegovina (Western Balkan Peninsula; Southeast Europe) carried out in the years 2006-2009 are presented. Despite the country's extraordinary high plant diversity with about 3600 known species of vascular plants, plant usage in traditional medicine remained largely unexplored in the past. The purpose of this study was the systematic collection of information about usage of wild and cultivated plants in human therapy from Bosnia and Herzegovina. Information was gathered by performing so called open ethnobotanical interviews by which data on the name, age and occupation of the interviewed person; the geographic locality and date of the interview; the name of the used plant; part of the plant used; the prescription background and preparation procedure as well as the indication was systematically collected. Plants mentioned to be used by the informants were collected, taxonomically determined and corresponding material was deposited in the herbarium of the Department of Pharmacognosy of the University of Vienna. In total, 34 places including villages and mountain areas were visited and 51 people, known as 'traditional healers' by the rest of the inhabitants, questioned. 228 wild and cultivated species and 730 different preparations for the use in human therapy were recorded. Species of the genera Achillea, Hypericum, Mentha, Teucrium, Thymus, and Urtica were particularly highly recommended by the majority of the informants. The most frequently mentioned indications were urogenital tract disorders, respiratory system disorders, gastrointestinal tract disorders, skin ailments, blood system disorders, nervous system disorders, cardiovascular system disorders, and rheumatism. Infusions were the most frequently prepared formulation. Other applied preparations mentioned with decreasing frequency were decocts, ointments, direct application of plants without prior preparation, fluid unctions, sirups and tinctures or collars, freshly pressed juices, powders, and finally macerations. Balms known as "mehlems" were special to Bosnia and were prepared from freshly chopped or freshly pressed herbal parts of various plants. Warmed resins from Abies or Picea species, bees wax, raw cow or pig lard, olive oil and honey were used as additives in the mehlem formulations. Representatives of the genera Arctium, Carlina, Euphrasia, Hypericum, Plantago, Teucrium, and Urtica were most frequently used in these balms. Prescriptions were verbally delivered, usually from mother to daughter and for even more than six generations. For the purpose of further analyses and comparisons, the collected data were inserted in the so called "VOLKSMED" data base of Austrian prescriptions. The identified broad variety of indications and their frequent applications suggests that traditional plant use is of high importance and still crucial for the medicinal accommodation of Bosnian people. Fifty-seven of the species reported by Bosnian people were used in official pharmacy. In addition, a variety of less known plants has been used since ages in traditional therapy of this country and hence may be potential sources for new therapies. Therefore, further pharmaceutical research into this particular and scientifically still underexplored proportion of Bosnian plant biodiversity appears promising and is recommended by the authors. (c) 2010 Elsevier Ireland Ltd. All rights reserved.