The Hang Seng Index lost 87.21 points or 0.36 percent to open at 23,828 on Monday.
Mainland stocks also opened lower with the benchmark Shanghai Composite Index down 0.12 percent at 3,467 and the Shenzhen Component Index down 0.2 percent at 10,488.
US markets, a key gauge of investor sentiment, were closed on Friday for a public holiday. (with additional reporting from Xinhua)
