In recent growing seasons, a new leaf blight was observed on potatoes (Solanum tuberosum L.) in various production regions in South Africa. Symptoms were observed before early blight, from 50-60 days after emergence of the potato plants. Leaf blight on potatoes caused by Alternaria alternata has previously been reported in Israel, Brazil and North America. This is, however, the first report of A. alternata causing leaf blight on potatoes in South Africa. Future research will focus primarily on management of this disease.