CBC News Network's Evan Solomon reports Dallaire is retiring because of a combination of issues: His desire to spend more time on post-traumatic stress disorder research and public speaking on international causes, ongoing struggles with PTSD, and frustration with the continuing Senate scandal.
Dallaire came to prominence in Canada after leading Canadian troops in Rwanda during the 1994 genocide.
His repeated warnings to the UN and to Canada went seemingly unheeded as Rwanda went through 100 days of killings.
Dallaire has also spoken publicly about his struggles since 1994 with PTSD.
Dallaire was named to the Senate by Paul Martin in 2005.