Anesthesiologists may have close relationship with muscle relaxants in clinical practice. Fourtunately, a few of the new muscle relaxants were discovered and used in clinic recently. Newly introduced non-depolarizing muscle relaxant: vecuronium has been clinically in use recently. The most suitable method for reversing the neurom uscular blockade caused by vecuronium continues to provoke discussion and differences of opinion. Simultaneous administration of neostigmine and atropine has been considered safe by some authors and dangerous by others. Both slow and rapid administration have been recommended. The general acceptance of the slow administration of neostigmine and atropine has been confirmed. In view of the various data on vecuronium reversal, neostigmine was compared with pyridostigmine and heart rate changes were studied. The results were as follows: 1) Recovery index after i.v. neostigmine 40 ug/kg and atropine 20 ug/kg when first twitch of the "train of four" was appeared during vecuronium 0.1mg/kg relaxation, was 129.9 sec. Heart rate change was decreased to 46.9/min(15%) after i.v. neostigmine during 16 to 20 minutes period(p<0.05). 2) Recovery index after i.v. pyridostigmine 160 ug/kg and atropine 20ug/kg when first twitch of the "train of four" was appeared during vecuronium 0.1mg/kg relaxation, was 134.0sec. Heart rate change was not statistically significant compared with neostigmine.