Popular depolarising muscle relaxant, suxamethonium (succinylcholine chloride), produces fasciculation in group of muscles and 'after pain'. Mode of its action is neuromuscular blockage. It also may be associated with muscle fibre injury and altered membrane permeability. These may cause rise of serum K+ and creatinine phosphokinase (CPK) levels. But use of diazepam either during or as pretreatment may reduce the fasciculation, 'after pain' and rise of K+ and CPK levels. Present study was undertaken to show whether any correlation of the degree of fasciculation and postsuxamethonium myalgia is present or not and whether diazepam has any role in reducing muscle injury and in turn reducing the levels of serum K+ and CPK.