Sugammadex, a modified gamma-cyclodextrin, is a selective relaxant-binding agent designed to reverse the effects of the steroidal neuromuscular blocking agents rocuronium or vecuronium. This study compared the efficacy of sugammadex and neostigmine for reversal of neuromuscular blockade induced by rocuronium for facilitating elective surgery. This randomised, multicentre, parallel-group trial included 98 adult patients. Patients received intravenous propofol for induction followed by sevoflurane maintenance anaesthesia. Neuromuscular blockade was monitored using acceleromyography and a train-of-four (TOF) mode of stimulation. Patients were randomly allocated to receive sugammadex 2.0 mg kg(-1) or neostigmine 50 microg kg (-1) (with glycopyrrolate 10 microg kg(-1)) at reappearance of the second response of the TOF (mean 16% twitch height of first response) after the last dose of rocuronium. Safety was evaluated by assessing adverse events, laboratory variables and vital signs. Time to recovery of the TOF ratio of 0.9 after sugammadex compared with neostigmine was significantly shorter (P < 0.0001), being 1.5 versus 18.6 min (geometric means). Predictability of response was greater with sugammadex than neostigmine: with 98% of sugammadex patients versus 11% of neostigmine patients recovering to a TOF ratio of 0.9 within 5 min. There were no clinical events related to residual neuromuscular blockade or reoccurrence of blockade. Serious adverse events were observed in two sugammadex-treated patients and in three neostigmine-treated patients, respectively, but none were considered related to study drugs. Sugammadex achieved significantly faster recovery of neuromuscular function after rocuronium to a TOF ratio of 0.9 compared with neostigmine (Clinicaltrials.gov identifier: NCT00451217).