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Sublethal effects were evaluated in subsequent generations of whiteflies Bemisia tabaci (Gennadius) arising from parental generations exposed in the four nymphal stages to the fungus Beauveria bassiana (Balsamo) Vuillemin. Examples of such effects include impaired fertility, production of malformations or external variations, and reduced survival of later generations. Malformations of the head, legs, wings or abdomen were not observed in adults derived from treated nymphs, nor were negative effects observed in the fecundity and fertility of the descendants of the whiteflies treated with the fungus. However, moulting problems were observed in insects descended from B. bassiana-treated whiteflies. This is the first time that such effects have been reported, with almost 30% of imagos resulting from treated nymphs unable to detach completely from the exuvia. A gradual reduction in mortality rates between subsequent generations was observed. The importance of these results is discussed in the light of findings from other studies into the effects of entomopathogenic fungi on pest insects.