He was 60.
Rabb died Sunday at the North Broward Medical Center in Deerfield Beach, Fla., said Mayapriya Long in a telephone interview from her brother-in-law's home in Hawthorne, N.Y.
A missionary with the Manhattan-based United Methodist Church's General Board of Global Ministries, Rabb had gone to Haiti to attend a meeting of aid organizations to improve medical services in Haiti.
Rabb was entering the lobby of the Hotel Montana to join some friends for dinner when the quake hit the capital city, Port-au-Prince.
Rabb, who ran the organization's office of mission volunteers, and two colleagues, the Rev. Samuel W. Dixon Jr. of North Carolina and the Rev. James Gulley of Denver, were buried beneath the toppled concrete.
"This man's whole life was ministry and helping the underprivileged," said Long. "He was always saying, 'What can I do?' 'How can I help?"'
The three men were buried for almost 70 hours, "trapped in a 3-foot by 5-foot by 8-foot space," said Long. "Clint and Sam's legs had cement and rebar on them, so that's why it took that many hours to get them out."
Their legs were amputated, she said.
Gulley, a consultant for the United Methodist Committee on Relief, survived. Dixon, who was head of the UMCOR, died in the earthquake.
Long said that despite what must have been his own excruciating pain, the family was told Rabb "kept picking up pieces of concrete and rearranging it around Dixon to make him more comfortable."
Like her husband, the Rev. Suzanne Rabb has also served as a missionary.
The couple came to New York from Austin, Texas, and were affiliated with a number of Methodist churches in Texas.
Rabb graduated in 1967 from Wolfe City High School in Hunt County, northeast of Dallas.
And held a Bachelor of Arts degree from Austin College in Sherman according to the Global Board of Global Ministries Web site.
Rabb traveled constantly, to third-world countries in Asia, Africa and Central and South America, Long said.
"He was one of those people who would say, 'Somebody's got to do it, it might as well be me,"' she recalled.
A memorial service was planned for Saturday at University United Methodist Church in Austin, Texas.