Sweet Katie Parker came to Springfield in 1977. A young nurse, from Madison, Wisconsin, Katie arrived at Cedars after Nurse Peggy Scott's exit. Needing a roommate, Katie struck gold when Nurse Hillary Kincaid answered her ad in the paper. In Hillary, Katie found not only a roommate but a friend as well. In 1979, Katie began dating Dr. Mark Hamilton. However, Mark didn't really feel the same way about her and played the field. Thinking his disinterest was on account of her being overweight, Katie left town briefly to attend a "fat farm." Later, Mark learned that Katie left the farm and had become an actress in New York.

By 1980, Katie returned and began dating the conniving Andy Norris. Meanwhile, in early 1981, files started disappearing from psychiatrist Sara McIntyre's office. Though Sara initially blamed Katie, and was ready to fire her for losing the files, Katie was able to reassure Sara that she knew nothing about the missing files. Meanwhile, Hillary and Floyd began to take an interest in one another. Unfortunately, for some reason, Katie was very uncomfortable with the idea of a close friend of hers dating her brother and began to give Hillary the third degree from Katie about dating her brother. Also causing friction between Hillary and Katie was the fact that Hillary had doubts about Katie's new boyfriend, Andy Norris's, Floyd had the same doubts and, unfortunately for Katie, they would be proven right when it was discovered that Andy was the one stealing files from Sara's office and using them to blackmail various Springfield citizens. Katie was deeply hurt by the betrayal of the man she took into her bed.

Afterwards, Katie had unsuccessful romances with Tony Reardon (who was more interested in Hillary than her) and his brother Jim (who also ended up falling for Hillary). Soon, a wary Katie decided to give up romance and focused on being an exceptional nurse and a good friend to those in Cedars. In late 1983, when fellow nurse Lesley Ann Monroe tried to kill herself because of her failed romance with Warren Andrews, Katie used her disastrous relationship with Andy to convince Lesley Ann that a man wasn't worth killing herself over. In 1984, Katie began dating Dr. Louie Darnell, however her prior romantic experiences kept her from giving herself fully to him. Finally around 1985, Katie, supposedly, met the man of her dreams when a young basketball player named Long John Reed was admitted to Cedars. In the meantime, Louie proposed marriage, but Katie was forced to turn him down since her feelings for him were strictly platonic. Within a short period, Katie received another proposal, this time from Long John Reed. Katie accepted the proposal and left town. Needling to leave town quickly, Katie didn't even have time to say a proper goodbye to her brother, Floyd, but instead gave a letter to head nurse Lillian Raines to give to him. A divorced Katie Parker came back, off-screen, when Floyd was arrested for murder in 1985.