The organism does not appear to be very host or tissue specific and can infect naturally a large number of avian and mammalian species. Chlamydiosis has been recorded in Germany, United States, Australia, Canada, France, Austria, Spain, England, Italy, Bulgaria, Romania, New Zealand, and Japan etc. The disease was identified in the country during 1973 from the cases of abortion from sheep and goats in India. Later on various workers also reported various disease manifestations in other animals from the country. The incidence has been recorded ranging from 20-70% in sheep and goats, which became as low as 2-15% in succeeding years. No significant role has been reported in experimentally induced infection in sheep and goats. Higher incidence of abortions in both primapara and multipara sheep and goats has been recorded. The perinatal mortalities due to intra- uterine infection have been described to vary from 5-50% both in lambs and kids. It has also been observed that an overall proportional foetal and neonatal mortality rates in lambs and kids during hebdomadal period (0-1 week) varied in lambs and kids whereas mortalities in post-hebdomadal period (1-4 weeks) declined both in lambs and kids. Most of the mortalities recorded during 0-1 week were within 72 h after the birth, which was attributed to the intra-uterine infection and also the immuno-suppression and/or deficiency of immunoglobulin in milk which might have contributed in interfering with the protection mechanisms during the neonatal period.