Patient is a yong man with diagnosis of botulism that is alert and intubated with mechanical ventilation because respiratory muscle weakness and after 3 days of antitoxin therapy ,one diluted vial every 4 hours, no improvement is seen .Iknow that antitoxin can not improve before weakness or paralysis but in our hospital there is not bioassay test and results of cultures prepare too late to make a decision and their answers are always susceptible.