Brooks' lawsuit against Integris Canadian Valley Regional Hospital in Yukon seeks the return of the December 2005 donation. The trial began Tuesday.
Brooks says hospital officials showed him mock-ups of buildings bearing Colleen Brooks' name and told him his donation was earmarked for such a project.
The hospital denies any wrongdoing and in court filings says Brooks' donation was "anonymous and unconditional."
Dressed in jeans and a black cowboy hat, Brooks shook hands with lawyers and made small talk before proceedings began Tuesday. He was accompanied by his wife, country singer Trisha Yearwood.
