The present invention relates to a process for preparing a highly pure neurotoxic component of a botulinum toxin by cultivating Clostridium botulinum under conditions that allow production of a botulinum toxin, and isolating the neurotoxic component from the botulinum toxin. In addition, the present invention relates to a highly pure neurotoxic component of a botulinum toxin obtainable by the process of the present invention and uses thereof.