OBJECTIVE To analyze electromyographic response and clinical effects after precurarization with vecuronium bromide (0.01 mg/Kg), also noting intubation conditions and the presence or not of fasciculations after administration of succinylcholine (1.5 mg/Kg). METHODS A single precurarization dose of vecuronium was administered to 20 patients 5 minutes before anesthetic induction for general surgery. During this period we monitored neuromuscular transmission of the cubital nerve in the wrist by electromyography with a series of 4 stimuli, expressing each as the percentage of the first response and of the ratio T4/T1. We also recorded clinical repercussions. General anesthesia was then induced; after administration of succinylcholine, the presence or not of fasciculations was noted and intubation conditions were evaluated. RESULTS The electromyographic response after precurarization was highly variable, as 4 different responses were recorded. We found potentiation phenomena in 20% of our patients, diminished response in 60%, fatigue phenomena in 15% and no change in 5%. Clinical signs noted were blurred vision and heavy eyelids. Fasciculations disappeared in 95% of the patients and intubation conditions were excellent. CONCLUSIONS Vecuronium at a precurarization dose produces highly varied but well-tolerated electromyographic responses. The drug is effective in eliminating fasciculations produced by succinylcholine and does not affect intubation conditions.