An extreme case of mass mortality of the sea fan Paramuricea clavata on the Portofino Promontory is reported. During October 1993 about 10,000 sea fans, living in the 20 to 35 m depth range, underwent a degenerative process, which caused the progressive detachment of the coenenchyma from the gorgonians' branches. About 80% of the affected colonies were reduced to a bare. It may be assumed that an increase in this mortality may be related to a violent storm that caused a drop in salinity and suspended sediment locally. Specific analysis has provided no evidence of bacterial involvement.