Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liividae), is the most important pest of citrus worldwide. It is the vector of the bacteria Liberibacter spp. responsible for Huanglongbing, a devastating disease of citrus. The pathogenicity of four Beauveria bassiana (Balsamo) Vuillemin (Hypocreales: Cordycipitaceae) strains and a commercial product were evaluated on immature stages of D. citri in laboratory bioassays. At a concentration of 1×10⁸ conidia per milliliter, neither the strains nor commercial product of B. bassiana had any effect on D. citri eggs; 95% of the eggs hatched and nymphs continued development into adults. The strains evaluated, Bb-Rhy, Bb-Dc, Bb-18, Botanigard, and Bb-Hy, killed 58, 56, 45, 43, and 21%, respectively, of all nymphs. The shortest lethal times, 8.5 and 9.5 days, were by Bb-Rhy and Bb-Dc strains. Bb-Rhy killed significantly more I-III than IV-V stage nymphs. Median lethal concentrations of the most pathogenic strains on nymph IV-V instars were 8.34×10⁶ conidia per milliliter by Bb-Dc and 1×10⁷ by Bb-Rhy. The impact of the fungus on nymphal stages was discussed.