As a result of the strong structural and functional similarities between the innate immune system of mammals and the insect immune response, insects have been exploited for evaluating the virulence of fungal pathogens of humans and for assessing the efficacy of anti-fungal agents. There is a strong correlation between the results obtained using insects and mammals and insects have the added advantage of being cheap to purchase, give results in 24-48 h and are without the ethical and legal restrictions associated with the use of mammals. Larvae of Galleria mellonella are excellent in vivo models and have been used with a variety of fungi and anti-fungal agents. Factors affecting the use of G. mellonella larvae are described and examples of where these larvae have been utilized are discussed. Â© 2010 The British Mycological Society.