Excretion of virus in the throat, urine, and conjunctiva of smallpox patients was studied daily for 2-3 weeks after the onset of fever. The virus titre in the throat and urine of haemorrhagic and confluent cases was higher than in discrete cases. The duration of virus excretion was also greater in confluent cases than in discrete cases. Conjunctival swabs from all 12 smallpox patients with conjunctivitis were positive for virus. The duration and titre of virus excretion in the throat, urine, and conjunctiva of patients were not related to their age or sex and did not depend on whether or not they had received a primary vaccination.