OBJECTIVE The aim of this study was to examine the effect of landiolol hydrochloride, an ultrashort-acting beta(1)-blocker, on suxamethonium-induced neuromuscular block. METHODS Thirty patients were randomly allocated to receive a loading dose of landiolol, 0.125 mg x kg(-1) x min(-1) for 1 min, followed by an infusion at 0.04 mg x kg(-1) x min(-1), or placebo. Twenty minutes after the infusion of landiolol or placebo, suxamethonium 1 mg x kg(-1) was administered during propofolfentanyl-nitrous oxide anesthesia. Neuromuscular block was monitored by train-of-four (TOF) responses of the adductor pollicis muscle, applying acceleromyographic stimuli to the ulnar nerve. RESULTS The onset of neuromuscular block did not differ between the groups. The time from administration of suxamethonium to spontaneous recovery to the first twitch of TOF (T1) of control was significantly longer in the landiolol group (mean [SD]; 12.2 [2.5] min), when compared with the control group (9.8 [2.6] min). However, the TOF ratios measured when the T1 had spontaneously recovered to 10%, 25%, 50%, 75%, 90%, and 100% of control was comparable between the groups. CONCLUSIONS Landiolol delayed recovery from suxamethonium-induced paralysis. However, the interaction between the drugs seemed to be small in the clinical setting.