Dr. Lawrence Hourani is a surgeon at Princeton-Plainsboro Teaching Hospital. He is always referred to either by just his last name or as "Dr. Hourani".
Hourani and House have a respectful but antagonistic relationship. Although they both respect each other's medical skills, House often interferes in Hourani's personal life and operations simply to make room on the operating schedule for House's own patients. Hourani rarely retaliates in kind, but he never hesitates to make fun of House's outbursts in front of the other hospital staff.
Dr. Hourani is first seen when he is performing a liver transplant on the patient, Keith Foster in the episode Detox. Based on an autopsy performed on the patient's dead cat Jules, House learned that he did not need a new liver. He entered the OR with a termite while he was non-sterile. Hourani refused to stop the transplant so House spat on him forcing them to stop it. Chase wanted to tell him to redo the surgery.
In the season four episode Alone, Megan Bradberry was suffering from internal bleeding. Dr. Hourani performed the surgery to help her. House and Cuddy watched it, House noticed something in her vagina indicating that she was recently pregnant. He entered the OR once again un-sterile, he stopped Hourani. He also noticed that there was scraping indicating an abortion.
In Two Stories House pretended to be Hourani during an auto accident with an advertising executive. However, he had to keep up the pretense when the ad man showed up at the same Career Day event that House was attending. However, the deception was short-lived when House mentioned a recent encounter with the real Hourani during his narrative.
Hourani's first name, Lawrence, is finally revealed in Two Stories on the sign on his office door. It is also revealed that Hourani has a very attractive, younger wife, and two children.