Sea buckthorn (Hippophae rhamnoides L.) is a native species in various regions of Asia and Europe. It is cultivated as a multipurpose horticultural species in northern temperate regions of Europe, Asia, and North America with large economic potential used for food, pharmacology, cosmetics, and environmental conservation. Diseases in natural populations and managed landscapes have increased, endangering sea buckthorn growth and cultivation worldwide. This review article focuses on sea buckthorn canker, wilt and decline diseases caused by pathogenic fungi, their distribution, hosts of involved pathogenic fungi and symptoms. Published information on sea buckthorn fungal diseases is available only about a few diseases, such as wilt (Verticillium dahliae), the dried-shrink disease caused by various fungi and abiotic factors, and stem canker (Hymenopleella hippophaeicola, Cytospora spp., Stigmina sp.). Some fungi reported on sea buckthorn are poorly studied, or the sea buckthorn is a newly discovered host, as in the case of Eutypa spp. The most often reported symptoms of these diseases are cankers and cracks on trunks and main branches, dead buds and leaves, necrosis of various tissues on branches, and root necrosis, resulting in the death of the shrubs. In general, the fungal diseases on sea buckthorn are not sufficiently addressed, and more research is needed.