Dennis was born on July 12, 1951. She began competing in local contests in 1981. Her earliest success was in mixed pairs competition, with partner Kevin Lawrence. They won several titles, including the 1985 IFBB World Amateur competition. Dennis earned her pro card by winning the overall title at the 1985 NPC Nationals. She then established herself as one of the top professional competitors by finishing third in the Ms. Olympia later that year. She competed in a total of nine Ms. Olympia contests, finishing outside the top ten only once. As a pro, Dennis won the 1986 Los Angeles Pro Championship and the 1989 Pro World Championship. She was inducted into the IFBB Hall of Fame in 2001.
