There are three major leaf diseases, now called Pseudocercospora leaf spot diseases of banana, which form the sigatoka leaf spot complex: Sigatoka disease (yellow Sigatoka) caused by Pseudocercospora musae, black leaf streak disease (black Sigatoka) caused by P. fijiensis and Eumusae leaf spot disease caused by P. eumusae. These diseases, especially black leaf streak disease, are a major constraint to banana cultivation and they occur across most of the global production zones of banana. This chapter gives an overview of the symptoms of the diseases, their taxonomy and diagnosis, population history and geographical distribution and provides some new insights into the disease cycle, epidemiology and the host–pathogen interactions which are required to underpin the development of more sustainable methods to control the disease through field management and the identification and deployment of effective resistance in the banana plant.