SUMMARYWe describe an outbreak of Q fever affecting 16 of 32 employees at a truck repair plant. None of the cases were exposed to cattle, sheep or goats, the traditional reservoirs of Q fever. The cases did not work, live on, or visit farms or attend livestock auctions. One of the employees had a cat which gave birth to kittens 2 weeks prior to the first case of Q fever in the plant. The cat owner fed the kittens every day before coming to work as the cat would not let the kittens suckle. Serum from the cat had high antibody titres to phase I and phase II Coxiella burnetii antigens. The attack rate among the employees where the cat owner worked, 13 of 19 (68 %), was higher than that of employees elsewhere, 3 of 13 (28%) [l' < 001]. The cat owner's wife and son also developed Q fever. None of the family members of the other employees with Q fever was so affected.We conclude that this outbreak of Q fever probably resulted from exposure to the contaminated clothing of the cat owner.