The keratinophilic soil fungus Chrysosporium tropicum was evaluated as a biological control agent against Anopheles stephensi larvae in the laboratory. Culture filtrates of C. tropicum were found to be toxic to An. stephensi larvae at various concentrations. The ranges of the 50% lethal concentration (LC50) values of fungal filtrates were 16.60-17.78, 12.02-12.88, and 34.67-35.48 microl/ml against 1st-, 2nd-, and 3rd-stage larvae, respectively. The ranges of LC99 values were 38.90-63.10, 12.02-213.80, and 74.13-109.65 microl/ml against 1st-, 2nd-, and 3rd-stage larvae, respectively.