Only one broadly neutralizing anti-HIV antibody, 2G12, recognises the envelope sugars of HIV. In the present study, we show that 2G12 also recognises Candida albicans and Candida tropicalis with high affinity (11 nmol/l) through a carbohydrate-dependent interaction (50% inhibitory concentration for D-fructose, 12 mmol/l). This is the first report of a neutralizing HIV antibody displaying cross-reactivity with another pathogen, revealing that the carbohydrate neutralization determinant of HIV, defined by 2G12, is more widespread amongst immunogenic, microbial surfaces than previously recognized.