Six intact Balami rams were experimentally infected with Anaplasma ovis. Another six were infected one month after splenectomy and six others served as controls. Clinical manifestations of the disease, first observed between 5 to 7 days post-infection, were more severe and prolonged in the splenectomised-infected than in the intact-infected group. There was progressive deterioration in semen quality, which was also significantly more severe and prolonged in the splenectomised than in the intact-infected rams. Following treatment with long-acting terramycine, clinical recovery occurred earlier in the intact-infected (1-4 weeks) than in the splenectomised-infected group (5-7 weeks). A similar pattern was observed in post-treatment improvement in the sperimiogram. However, although the infected animals recovered clinically by 1-7 weeks post-treatment, restoration of the reproductive potential did not occur for 20 to 25 weeks. It appears that stress factors may aggravate the deliterious effects of anaplasmosis.