The crash happened on the M4 at Lidcombe about 2.30am today.
Paramedics treated a 25-year-old female driver of a Kia Cerato for minor injuries at the scene.
She was then taken to Westmead Hospital for blood and urine testing.
The 26-year-old male driver of a Toyota Yaris was taken to Westmead Hospital, while the 23-year-old female passenger was conveyed to Concord Hospital.
Both are listed as being in a stable condition. Two other passengers in the vehicle were uninjured.
The 26-year-old male driver and two passengers from a Toyota Corolla suffered minor injuries. Neither required hospitalisation.
The Cerato reportedly rolled seven times and the crash scene was spread over 300m, police said.
Detectives are investigating whether alcohol was a factor.
