Leek (Allium porrum L.) plants showing a distinct yellow streaking of the leaves were found to be infected with a flexuous, rod-shaped virus, approximately 700 nm long. On the basis of symptoms, host range, particle morphology, and serology, this virus was indentified as leek yellow stripe virus. In New Zealand, this disease has been reported from only one property in the Hastings area where an incidence of nearly 100% was recorded in 1978 and 1979.