This paper brings together historical questions about the nature of assimilation and the medicalisation of migrants in the post-war era, with a focus on medical writings about migrant patients in Australia in the 1950s and 1960s. It argues that physicians adopted official assimilation ideologies to construct a “New Australian patient” whose beliefs and behaviours indicated a less sophisticated understanding of medicine, and who suffered particular psychosomatic illnesses and health risks linked to their migration, socio-economic status and linguistic isolation. By making assimilation medical, these doctors helped bridge the cultural gulf that existed between Australian doctors and their migrant patients, but they also perpetuated cultural stereotypes through which certain unassimilable groups were blamed for their own medical problems.