Series regulars of Doctors were met by series producers and executive producers for several rounds of auditions prior to their casting. Series producer Lloyd stated that as well as looking for talent, they looked for somebody who was able to fit into the team of hardworking cast members due to the heavy filming schedule. Once they had been cast, actors were given detailed notes about their character, including their backstory, personality, characterisation and any other relevant details. Earlier episodes included a noticeably smaller cast, with episodes more self-contained. However, with the increased number of episodes, the cast also increased to include continuing storylines. The original nine regular characters to be introduced in Doctors were Anoushka Flynn (Carli Norris), Joanna Helm (Sarah Manners), Kate (Maggie Cronin) and Mac McGuire (Christopher Timothy), Caroline Powers (Jacqueline Leonard), Helen Thompson (Corrinne Wicks), Rana Mistry (Akbar Kurtha), Ruth Harding (Yvonne Brewster and Steve Rawlings (Mark Frost).
Series regulars of Doctors were met by series producers and executive producers for several rounds of auditions prior to their casting. Series producer Lloyd stated that as well as looking for talent, they looked for somebody who was able to fit into the team of hardworking cast members due to the heavy filming schedule. Once they had been cast, actors were given detailed note,s about their character, including their backstory, personality, characterisation and any other relevant details. Earlier episodes included a noticeably smaller cast, with episodes more self-contained. However, with the increased number of episodes the cast also increased to include continuing storylines. The original nine regular characters to be introduced in Doctors were Anoushka Flynn (Carli Norris), Joanna Helm (Sarah Manners), Kate (Maggie Cronin) and Mac McGuire (Christopher Timothy), Caroline Powers (Jacqueline Leonard), Helen Thompson (Corrinne Wicks), Rana Mistry (Akbar Kurtha), Ruth Harding (Yvonne Brewster and Steve Rawlings (Mark Frost).