[[abstract]]The genus Hypericum (Clusiaceae) in Taiwan was taxonomically revised based on morphological, palynological, cytotaxonomic, phytogeographical, and ecological studies. Twelve species and two subspecies are recognized. Hyericum geminiflorum subsp. trinervium, which was previously treated as synonymous with H. geminiflorum subsp. geminiflorum., is now treated as distinct. The record of H. laxum by Lu (1976) is treated as synonymous with H. japonicum. Morphology of pistils and sepals are valuable characters for the classification within the genus in Taiwan. Besides, leaf and fruit shapes and distribution patterns of glands also provide useful information. Seed micromorphology displays more or less interspecific difference, but is unable to distinguish closed related taxa. Observation of chromosome numbers reveals some variations among species. The chromosomes numbers of H. formosanum (n=21), H. geminiflorum subsp. simplicistylum (2n=42), H. sampsonii (n=10), and H. subalatum (n=21) are determined for the first time. Biogeographically, most taxa are allopatric distribution. Some species, H. erectum, H. formosanum, H. nakamurae, H. nokoense, and H. subalatum, have very narrow range of distribution.