Mycoplasma wenyonii and ;Candidatus Mycoplasma haemobos' are pathogens associated with bovine hemoplasmosis. Hematological parameters of these two hemoplasma species were compared in a cattle herd that was known to be infected with these 2 pathogens. ;C. M. haemobos'-infected cattle exhibited lower red blood cell levels, hemoglobin concentrations and packed cell volumes than M. wenyonii-infected cattle and hemoplasma-negative controls. On the other hand, cattle infected with M. wenyonii did not show any significant differences in hematological parameters compared with the hemoplasma-negative cattle.