Knowledge of indigenous cultures about medicinal uses of local plants is an important input for understanding traditional utilization of biological resources, for promoting community healthcare practices and also for developing modern plant based drugs. A study was therefore undertaken in Coastal Karnataka, a culturally and floristically diverse region between the Western Ghats and the Arabian sea in India, to document and analyse the ethnomedicinal practices and plants of the area. The study was a part of an ongoing ethnobotanical documentation program started in 1995. Information on disease concepts, treatment methods and plants used is collected from herbal healers and knowledgeable elders of indigenous communities using standard ethnobotanical methods of questionnaire-based personal interviews in the field. Simultaneously, plant materials were also collected which were processed and preserved for botanical authentication. This study resulted in the documentation of 917 methods of herbal treatment for 42 various health problems which involves 342 species of plants belonging to 34 families. Number of plants used in these methods range between 1 and 17. Major categories of diseases treated are: skin diseases (22%), pains and swellings (20%), gastro-intestinal and urino-genital (15% each). Among the plants used, 30% are herbs, 27% trees, 25% climbers and 18% shrubs. Bark of the stem is the predominantly used part (30%), followed by leaves (22%), roots (16%), fruits or seeds (12%) and entire plants (11%). The dominant families of ethnomedicinal plants were: Fabaceae with 38 species, Euphorbiaceae (22 species), Rubiaceae (11 species), Acanthaceae, Asteraceae, Apocynaceae and Rutaceae (10 species each). Majority of the plants are used against several diseases, either alone or in combination with other plants. 12 species are used in the treatment of 10 or more diseases whereas 72 species are used against 5 or more diseases. The most popular medicinal plants, in terms of the number of diseases against which they are used, are Cyclea peltata, Aristolochia indica (19 diseases each), Cuminum cyminum (17), Curcuma longa (13), Asparagus racemosus (12), Ficus racemosa (12), Hemidesmus indicus (12), Ficus religiosa (11), Calotropis gigantea (11), Vitex negundo (11), Aegle marmelos (10) and Leucas aspera (10). Comparison and analysis with similar literature from other areas and available phyto-pharmacological data provided indirect supportive evidences for many of the medicinal claims recorded during the present study.