Firefighters rushed to the property in Newbridge, Wolverhampton, in the early hours to find a 75-year-old and 50-year-old trapped in a bedroom on the first floor.
Liquid fire accelerant had been poured through the letterbox of their Riches Street home and the fire had started on the ground floor.
Both women were taken to New Cross hospital for precautionary check-ups after breathing in smoke.
West Midlands Ambulance Service confirmed that they were called to the scene at 3am, sending an ambulance and a paramedic support officer.
They assessed two patients at the scene before taking them to hospital at 4.08am.
West Midlands police also attended the blaze. In a statement they said: "We were called by the fire service to reports of a fire in Riches Street just after 3am today.
"Two women were in the property at the time, of which one was aged in her 70s, and suffered from smoke inhalation.
"It is suspected of being arson and a police investigation has been launched."
Anyone with information should contact the police on 101.