Daniela Merighetti of Italy was second and Anna Fenninger of Austria was third.
American ski star Lindsey Vonn, who posted the fastest time in the first training run, did not ski Thursday.
Her teammate Stacey Cook said Vonn did not feel well in the morning.
"I had breakfast with her this morning and she seemed cheery and her normal self, so somewhere between breakfast and here I guess she wasn't feeling well," Cook said. "She'll be ready for tomorrow, I know it. She'll make all of us look bad again."
The first of two women's downhills at Lake Louise is scheduled for Friday. The women will also race super-G on Sunday.
Vonn swept all three races last year. She's won 11 career World Cups at Lake Louise.
Rolland's previous best result in a Lake Louise downhill was seventh in 2010.
Larisa Yurkiw of Owen Sound, Ont., is the lone Canadian racing downhill at Lake Louise. She was 35th.