Vic Howe, who played three seasons for the NHL's New York Rangers in the 1950s, died on Saturday in Moncton, N.B.
Howe's sister, Helen Cummine, said the 85-year-old had dementia and suffered a cardiac arrest.
"It was very, very hard," she said.
Cummine, who lives in Saskatoon, said family members coming to the city to celebrate Gordie Howe's career at a celebrity sports dinner on Friday will probably gather to remember Vic.
She added that Gordie and Vic were particularly close and when Gordie was told about his brother's death "there were quite a few tears shed."
"He must have understood," she said. "We're all up in age, so every day is a blessing."
Gordie Howe, who is 86, suffered two disabling strokes late last year. His family has said his health has improved after he underwent a stem-cell treatment as part of a clinical trial in Mexico.
Known as "Mr. Hockey," Howe holds NHL records for most games played (1,767) and seasons played (26). His 801 career goals rank second to Wayne Gretzky's 894.
The Hall of Famer played on four Stanley Cup championship teams in Detroit during a 25-year stint that began in 1946.
Cummine, 80, said Howe is excited to return home to Saskatoon.
"When they get off the plane (tomorrow), instead of going to the hotel, Gord wants to come right here," she said. "You go along thinking all these years thinking he's just a brother, and then you see all this outpour of love and support that people have shown.
"It makes your heart grow a little bigger."