At 9:50 a.m. ET (1350 GMT), the Toronto Stock Exchange's S&P/TSX composite index was up 35.46 points, or 0.23 percent, to 15,469.07.

The gains came as investors awaited a vote on a US healthcare bill, seen as a test of President Donald Trump's ability to pass his legislative agenda, including tax cuts and infrastructure spending that could boost economic growth, through Congress.

TransCanada's shares rose 1.1 percent to C$62.44, while the overall energy group gained 0.3 percent.

Prices of oil, one of Canada's major exports, were boosted by hopes that an Organization of the Petroleum Exporting Countries output cut was beginning to balance a long-oversupplied market.

US crude prices were up 0.4 percent at $47.89 a barrel, while Brent crude added 0.4 percent to $50.77.

Nine of the index's 10 main groups rose, including a 0.2 percent gain for the heavyweight financials group, while industrials rose 0.4 percent as railroad stocks gained ground.

The materials group, which includes precious and base metals miners and fertilizer companies, lost 0.2 percent, while spot gold was little changed.