The Closer Economic Partnership Arrangement (CEPA) is a bilateral preferential agreement signed among China, Hong Kong, and Macao which opens up the China market by providing zero tariff after accession. This paper sheds light to the impacts of the CEPA on merchandise trade with an in-depth analysis on export efficiency. Despite that merchandise trade has already been fully liberalized, the estimation results indicate that the efficiency of exports to China has been on the decline since 2000. This implies that the actual value of exports to China has departed from its full potential, and confirms our suspicions on the incapability of the CEPA to boost the exports of Hong Kong and Macao to China. There is also no evidence to support that the CEPA has successfully attracted foreign investment to Hong Kong and Macao for tariff free exports to China.