Botulinum toxin type B (BoNT-B; Myobloc™) is a new botulinum toxin with demonstrated efficacy in patients with cervical dystonia, and has been found to decrease neck pain associated with this disorder. Developmental work has led to the commercial-scale production of a uniform, highly purified toxin complex in a liquid formulation. Production of BoNT-B involves fermentation, recovery and purification from Clostridium botulinum. The reliability and robustness of the process were tested by altering critical process parameters (eg, pH, temperature) and showing that a high-quality product resulted even in conditions detrimental to C botulinum fermentation. Consistency and key quality attributes (purity, complex integrity, percent nicking, specific activity) of the toxin were assessed using a series of biochemical tests, which were validated as precise and accurate and are now routinely used in quality control analysis. Results confirmed production of an intact, uniform toxin complex with consistent purity, percentage nicking (a measure of toxin activation) of over 70%, and specific activity over 90 U/ng in three manufacturing runs. BoNT-B is manufactured as a slightly acidic liquid formulation that maintains complex integrity, reducing the potential for generating neutralizing antibodies. The potency of drug substance, dilute bulk solution, and finished product was shown to be reliable using the validated mouse intraperitoneal LD50 potency assay. The liquid formulation of BoNT-B was found to be stable for at least 9 months at 25°C and at least 3 years at 2–8°C. BoNT-B has a long shelf-life and may be produced on a commercial scale reliably and reproducibly, making it readily available and convenient to store and use. Support of Elan Pharmaceuticals is gratefully acknowledged.