Abstract A description is provided for Nectria coccinea . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Fagus sylvatica (beech) DISEASE: Beech bark disease, in association with beech scale ( Cryptococcus fagi [Cryptococcus fagisuga] ); this is the most serious disease of beech in Britain. It has also been reported as pathogenic to Ganothus velutinus (49, 1677). The perithecia are also frequently found on many other hard wood and coniferous trees. GEOGRAPHICAL DISTRIBUTION: In association with beech bark disease it is only known in Europe (Denmark, France, UK) and eastern North America. It is common in northern Europe on other hosts probably as a saprophyte and it has also been recorded in Australia, Hong Kong, India and New Gledonia. TRANSMISSION: Ascospore discharge is associated with wet conditions (54, 5092). The ascospores are disseminated in air and penetration of the host is through bark fissures or bark wounds caused by scale insects (54, 5560).