To compare the efficacy and safety of Korean botulinum toxin A (KbtxA, Pacific Pharmaceuticals, Korea) against Botox in the treatment of essential blepharospasm, we performed a double-blinded, randomized, comparative trial comparing KbtxA and Botox for treatment of blepharospasm in 60 patients of the intention to treat population and 52 patients (26 patients from each group) of the per protocol population. The improvement of severity of spasm (SS) at 4 weeks post-injection as a primary efficacy outcome, qualifying non inferiority to the control group, Changes in eyelid closure force (CF) and functional visual status (FVS) after injection for secondary efficacy outcomes, and adverse effects for safety evaluation. Improvement of SS was noted in 90.3% of the KbtxA group and 86.2% of the Botox group. There were no significant differences between treatment groups in the changes of CF and FVS after injection (p>0.05). Adverse effects developed in 16.1% of the KbtxA group and 27.6% of the Botox group, but no serious adverse events were found in either group. KbtxA was not inferior to Botox in treatment efficacy and was clinically safe with no serious adverse effects when used to treat essential blepharospasm.