Located at the corner of State and Superior streets, the cathedral doors opened to worshippers for the 6 a.m. service.
Last winter a piece of decorative wood fell from the cathedral ceiling. An inspection found 4,000 other pieces were either loose or missing. Each one was removed by hand and repaired.
Workers will continue to fix broken and loose pieces of the ceiling towering over the catheral seating area, but officials have determined that there is no longer a danger to people gathered below.
"We have re-opened the big doors to parishioners, Chicagoans downtown, people from all over the United States, and friends from around the world. Join us at beautiful Holy Name Cathedral – where Chicago goes to pray!" the Cathedral's Web site quotes its pastor, Father Dan Mayall.