Previous reports revealed the importance of Thailand for diversity, systematics and evolution of powdery mildews. This report provides records of four additional species and variety belonging to the genus Erysiphe sect. Uncinula (Erysiphales) found in Thailand. Morphological descriptions of powdery mildew specimens found on hosts of four families and molecular phylogenetic analyses based on 28S rRNA gene and rDNA ITS sequences are provided. Three new records of Erysiphe sect. Uncinula spp. for Thailand are listed, and E. liquidambaris var. acalycinae is described.