Indonesian stocks were trading lower on Monday, a day before its central bank meets to review policy, while the Philippine main index was down after hitting record closing highs several times this month.
"Across the region, trading was lethargic. In our case, one of the reasons is profit-taking. We crossed the 8,100 level early in the year and valuations have been stretched already," said Justino Calaycay, analyst at Accord Capital Equities Corp in Manila.
The Jakarta composite index was on track to fall for a second straight session.
The country's central bank is expected to hold its key policy rate steady on Tuesday.
Singapore looked set to close at its highest level in more than seven years.
The city-state's central bank could loosen monetary policy for a second time this year on Tuesday, but analysts are divided over the magnitude of any easing.
The Malaysian index edged up after three days of losses, helped by mostly positive energy stocks.
Petroliam Nasional Bhd's (Petronas) chemical arm, Petronas Chemical Group Bhd, and Sapurakencana Petroleum Bhd were both up nearly 1 per cent.
Oil prices inched up on Monday following a strong session on Friday, as financial traders increased their bets on higher prices amid a slowdown in US drilling, but analysts warned fundamentals remained weak.
The Thai market is closed on April 13-15 for a new year holiday.