An outbreak of disease associated with cryptosporidia on a red-legged partridge (Alectoris rufa) game farm is described. Morbidity (diarrhoea and cough) was between 60% and 70% during the first weeks of life (4 to 25 days) and mortality was higher than 50%. The results of bacteriological and virological analyses were negative. Histological examination and antigenic diagnosis by enzyme-linked immunosorbent analysis revealed the presence of Cryptosporidium spp. in respiratory and intestinal tracts. The application of polymerase chain reaction-restriction fragment length polymorphism techniques and sequencing of a Cryptosporidium oocyst wall protein gene fragment confirmed the existence of Cryptosporidium meleagridis in faecal samples. The results obtained suggest that avian cryptosporidiosis should be included among respiratory and enteric diseases routinely tested for in farmed birds. © 2007 Houghton Trust Ltd.