A new disease of lily (cv. Star Gazer) caused by Phialophora mustea Neergard is described from some greenhouse at Castiglione del Lago (Perugia) in central Italy. Symptoms of the disease were stunting, leaf yellowing and rot of bulbs and roots. The fungus was examined for colony morphology, sporulation and pathogenicity. Artificial inoculations carried out in greenhouse showed the pathogenicity of P.mustea on lily; leaf yellowing, stunting and rot of bulbs and roots began to appear approximately sixty days after inoculation; afterwards, they were more evident and severe. This is the first-known report of the disease on lily and of P.mustea as a plant pathogen.