A survey of pathogens of Monochamus alternatus, a vector of Bursaphelenchus xylophilus, was carried out in China. Ten entomogenous fungal species and one bacterial species were identified on M. alternatus in pine forests in Anhui and Jiangsu provinces, of which Aspergillus flavus, Alternaria alternata, Fusarium moniliforme, F oxysporum, F solani, Paecilomyces farinosus, Verticillium lecanii and Serratia marcescens were new records on M. alternatus in China and Beauvernia bassiana was the prominent species. Fusarium oxysporum, A. flavus, B. brongniartii and S. marcescens were frequent species. Two different species of fungi or one species of fungus and one species of bacterium were found on the same M. alternatus larva. About 1-5% of larvae were diseased or infected by the pathogens.