We report on a 3-month-old girl with culture-confirmed infant botulism caused by a rare double toxin-producing Clostridium botulinum type Ba. This case was not related to honey-feeding. The clinical course was prolonged, with minimal spontaneous improvement at onset, and a period of fluctuating motor weakness and nasogastric feeding dependence afterward. Neurophysiologic studies produced normal results. Human botulism immune globulin was administered empirically on day 23 of presentation, with rapid full recovery. This case highlights the importance of pursuing diagnoses of infant botulism despite normal results of neurophysiologic testing and no history of honey-feeding. Our case also demonstrates a favorable response to human botulism immune globulin, despite the relatively late treatment.