Technical Abstract: Cryptosporidium galli Pavlasek, 1999 is described from the faeces of birds adding molecular and biological data. Oocysts are ellipsoidal, are passed fully sporulated, lack sporocysts, and measure 8.25 x 6.3 m (range 8.0 ¿ 8.5 X 6.2 ¿ 6.4 m) with a length to width ratio 1.30 (n=50). Oocysts are structurally similar to those of Cryptosporidium baileyidescribed from hens but in addition to being considerably larger than oocysts of C. baileyi, these oocysts infect the proventriculus in a variety of birds and not the respiratory tract. Oocysts were successfully transmitted from hens to chickens and morphologically similar oocysts were also observed in a variety of exotic and wild birds (Order Passeriformes, Phasianidae, Fringillidae and Icteridae). Molecular and phylogenetic analysis at the 18S rRNA, HSP-70 and actin gene loci demonstrate this species is genetically distinct from all known species and genotypes of Cryptosporidium, thus was named as Cryptosporidium galli.