A severe fruit drop and drying out was observed on Coffea arabica L. (Coffee) plantation at the Faculty of Agriculture, Chiang Mai University, Thailand in November 2022. About 40 % of the plantation was affected by the disease. Sooty mold fungi were observed on the fruit surface and the fungus was isolated using single spore isolation. Pathogenicity assays were performed on wounded and unwounded coffee fruits with a viable spore suspension of the isolate. The fruit rot disease symptom was observed after three days in wounded fruits. The pericarp turned from green to dark brown at the inoculation site. The pathogenicity assay fulfilled Koch’s postulates and our isolate was identified as the pathogen. The fungal morphology reveals that the isolate closely resembles Leptoxyphium. The phylogenetic placement of the isolate was confirmed using concatenated ITS and LSU phylogeny. The phylogeny revealed confirmed the isolate belongs to Leptoxyphium. The Leptoxyphium species are well-known epiphytic species and the current study proves that our Leptoxyphium isolate can colonize the plant tissue and cause the disease.