Conoideoxime A (1), a prenyl-tryptophan dimer possessing bis-oxime functionality, was isolated from cultures of the whitefly pathogenic fungus Conoideocrella luteorostrata BCC 76664. The structure was elucidated by spectroscopic analyses. It displayed antibacterial activity against Gram-positive bacteria, Bacillus cereus, Enterococcus faecium, and Staphylococcus aureus, with MIC values of 3.13, 6.25, and 6.25 lg/mL, respectively.