The study aims to provide a systematical revision of the traditional use of wild and cultivated plants in north-eastern Bosnia and Herzegovina (Western Balkan Peninsula; Southeast Europe). Thereby, it will extend and complement a recent previous study carried out in middle, southern and western Bosnia and Herzegovina. Information was collected by performing so called open ethnobotanical interviews. The following data were recorded and systematically assembled in a database: name, age and occupation of the interviewed person; the geographic locality and date of the interview; the name of the used plant; plant parts used; prescription background and preparation procedure as well as indication. Plants mentioned to be used by the informants were collected during field trips done together with the informants and taxonomically determined. The corresponding material was finally deposited in the herbarium of the Department of Pharmacognosy of the University of Vienna for the purpose of documentation. In total, 45 places including villages and mountain areas were visited and 84 persons questioned. 254 wild and cultivated species and 1655 different preparations for the use in traditional human therapy were recorded. The most frequently mentioned indications were disorders of the gastrointestinal tract, respiratory system, urogenital tract, skin, blood system, cardiovascular system, nervous system as well as rheumatism. Infusions were the most frequently prepared formulation. Other applied preparations mentioned with decreasing frequency were decocts, sirups, tinctures, collars, direct application of plants without prior preparation, ointments, freshly pressed juices, oils, powders, fluid unctions, macerations and finally suppositories. Special preparations, typical only for the area of Bosnia and Herzegovina were "mehlems" and some kind of sirup called "đulbe šećer" (eng. đulbe sugar). While "mehlems" were already recognized and accordingly discussed for the central, southern and western parts of Bosnia and Herzegovina, "đulbe šećer" seems to be known in north-eastern region only. The main compounds of this preparation are sugar or honey, lemon and flowers of one particular species of Rosa (with very small flowers), in Bosnia called "đulbe" rose or "sugar" rose. Prescriptions were verbally delivered for up to more than six generations, traditionally from mother to daughter. For the objective of further analyses and comparisons, the recorded data were inserted in the "VOLKSMED" data base of Austrian prescriptions. The study showed that there exist considerable similarities in medicinal plant use including indications and type of preparations between the different regions and ethnicities of Bosnia and Herzegovina. Interestingly, there were also only little differences in frequencies of medicinal plant use, indications and preparations between middle, western and southern part Bosnia and Herzegovina on one hand and the eastern, northern and north-eastern part of this county on the other hand. The results also demonstrated the high importance of medicinal plants for the physical health of Bosnian people. 70 of the species reported by Bosnian people were also 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. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.