Intoxication with botulinum neurotoxin, which occurs frequently in Poland, may cause serious diagnostic difficulties. As no assays for laboratory detection of botulinum toxin are available and the biological test on mice requires time before results are obtained, diagnosis must be based on clinical findings and patient's epidemiological history. Quick diagnosis and early administration of therapy with equine antitoxin is essential for patient's recovery. The effectiveness of antitoxin therapy is considered to be significantly reduced if the treatment is not started shortly after the onset of the disease. We describe a case of a patient in whom, because of diagnostic difficulties, antitoxin therapy was introduced with much delay. However, it proved highly efficient and lead to gradual recovery.