The present study was designed to compare the intubating conditions of rocuronium giving by “a modified timing principle” in rapid induction and intubation (RSII) with that of the gold standard, succinylcholine.

One hundred and twenty-four patients were randomly divided into rocuronium group (group R, n = 62) or succinylcholine group (group S, n = 62).

In group R, after rocuronium 0.6 mg kg-1 was given, anaesthesia was induced with propofol 2 mg kg-1 and remifentanil 2 μg kg-1, and tracheal intubation was performed 60 s after rocuronium administration.

In group S, succinylcholine 1.5 mg kg-1 was given after patient lost consciousness induced by the same regimen of group R, and tracheal intubation was performed 60 s after succinylcholine administration. Our primary endpoint was the intubating conditions.

The numbers of patients with excellent and good intubating conditions in group R were 90.0% and 6.7%, respectively, which were comparable with those in group S (91.7% and 5.0% respectively). The apnoea time in group S (79.7 ± 5.1 s) was longer than that of group R (56.6 ± 4.6 s) (p = 0.0063).

The average BIS values at the time of intubation in group R (64.1 ± 4.1) was higher than that of group S (43.2 ± 5.5) (p = 0.018).

In the context of a RSII with lidocaine–remifentanil–propofol, the application of this “modified timing principle” with rocuronium 0.6 mg kg-1 could provide comparable intubating conditions with those achieved by succinylcholine 1.5 mg kg-1.