The incidence and intensity of muscle fasciculations as well as the occurrence of cardiac arrhythmias following succinylcholine were evaluated in 36 premedicated children (1.0-5.7 years) after intravenous induction with thiopentone or after inhalation induction with isoflurane (3.75 vol-% in 70% nitrous oxide in oxygen). The study was randomized. In the thiopentone group, fasciculations were seen in all children and in the isoflurane group in 5 of 18 children (P < 0.001). The median of the duration of fasciculations was 15 s with a minimum of 5 s and maximum of 36 s (1st quartile 9 s and 3rd quartile 20 s) in the thiopentone group and 0 (0-15) s with a 1st quartile of 0 and a 3rd quartile of 3 s in the isoflurane group (P < 0.001). No cardiac arrhythmias were noted in either group. In conclusion, isoflurane in nitrous oxide inhibits succinylcholine-induced muscle fasciculations in children.