Abstract: The quality of oil palm (Elaeis guineensis jacq.) in nursery stage seedlings can be reduced by several diseases, particularly leaf blight and leaf spot, with equal adverse effect on market value. This research was conducted to evaluate these diseases in nursery stage of oil palm seedlings collected from eleven provinces in southern Thailand. A total of 197 fungal colonies were isolated from 277 disease samples. Based on morphological characterization and disease symptoms, the major fungal isolates found in this study in decreasing order belonged to the genera Curvularia 149 isolates and Colletotrichum 48 isolates, with disease incidence in decreasing order of Curvularia (61.01%) and Colletotrichum (22.38%). This report indicates the increasing importance of leaf spot disease in Thailand and the need for effective disease management. To design an effective method for controlling leaf spot diseases in nursery stage, further biological and chemical applications are needed.