This study compared the doses of sugammadex needed for rapid recovery from deep neuromuscular blockade (NMB) between young and elderly adults. Twenty-two young (20–40 yrs) and 22 elderly (≥70 yrs) adults were enrolled, and deep NMB of 1–2 post-tetanic counts was maintained with rocuronium intraoperatively. Predetermined doses of sugammadex were given at the end of surgery starting at 4.0 mg/kg for the first patient of each group. Doses were decreased or increased in following patients by 0.5 mg/kg, depending on the ‘success’ or ‘failure’ of rapid recovery in the preceding patient. ‘Success’ was defined as adequate recovery (train-of-four ratio 0.9) within 2 min. after sugammadex administration. The median (range) of ages was 29 (20–40) and 73 (70–84) yrs for the young and elderly adults, respectively. Doses of sugammadex facilitating adequate recovery from deep NMB within 2 min. in each patient population with 50% and 95% probability were defined as ED50 and ED95, respectively. The ED50 estimated by the Dixon's method was significantly higher in the elderly compared to young adults [4.2 ± 0.4 mg/kg versus 3.3 ± 0.3 mg/kg, p < 0.001]. The ED50 (83% CI) estimated by isotonic regression was 4.5 (4.2–5.0) mg/kg in elderly adults and 3.3 (3.2–3.4) mg/kg in young adults. The ED95 (95% CI) estimated by isotonic regression was 5.4 (4.9–5.5) mg/kg and 4.4 (3.9–4.5) mg/kg in the elderly and young adults, respectively. In conclusion, dose adjustments of sugammadex should be considered when rapid recovery from deep NMB is needed in elderly adults.