Cases of botulism in a family in eastern Anatolia were studied. In late September 2005, an outbreak of botulism developed in our region, first in 2 patients, a teenage boy and his mother, in whom the disease culminated in respiratory insufficiency and death. An additional 8 cases of botulism were identified later; most of them presented to our medical centre the next d. These patients with milder symptoms recovered gradually. All the patients received anti-botulinum toxin. The investigation of the source of the outbreak showed an unexpected vehicle for botulism infection in the these patients, suzme (condensed) yoghurt buried under soil. Type A botulinal toxin was detected in the yoghurt sample. The clinical diagnosis was also confirmed by a mouse bioassay performed with the serum samples of the patients. The most common symptoms were dry mouth, difficulty in speaking and swallowing, and change in voice quality. The 10 identified patients with botulism constitutes the largest-ever outbreak of botulism reported in Turkey to date. The present study shows the importance of considering a diagnosis of botulism soon after patients present with acute cranial nerve dysfunction and of promptly treating suspected cases with antitoxin.