House selected three doctors for his new diagnostic team in season 4. After the original team changed, Gregory House turned the hiring process into a competition involving a large group of applicants.
The season begins with House attempting to replace or rebuild his staff after Cameron, Chase, and Foreman move into new professional circumstances. He initially evaluates dozens of candidates through unusual tests and competitive assignments rather than a conventional interview process.
The three doctors ultimately chosen were Lawrence Kutner, Chris Taub, and Remy “Thirteen” Hadley. Foreman later returned to the group, making the working team larger than the three new hires. Amber Volakis was a major competitor but was not selected as one of the final three.
The number is sometimes confused with the number of original fellows or with the size of the expanded team after Foreman’s return. The question concerns House’s new selections from the season 4 competition, not every doctor who eventually worked in Diagnostic Medicine.