A case of moderately severe botulism was diagnosed in a 4 weeks old white female. Clostridium botulinum toxin was identified repeatedly in the infant's faeces by means of the mouse protection assay. Clostridium botulinum was isolated in pure culture from faecal material. Both the organism and the toxin were type B. The onset of illness was characterized by mild constipation, apathy, weak sucking and difficulty with swallowing. Incipient, probably aspiration, pneumonia was diagnosed at the same time. Further signs of botulism developed during hospitalization, viz. loss of head control, pooled oral secretion, weak cry, mild ptosis, reduced facial expression, generalized muscular weakness and reduced spontaneous activity. A nasogastric feeding tube was needed because the ability to suck and swallow was impaired. Immediately on admission of the infant to hospital emergency treatment was started with ampicillin, which was followed by penicillin injections. The infant recovered in 60 days. Subsequent medical examinations demonstrated that the recovery was complete and the development normal. The case represents the first instance of infant botulism detected on the European Continent.