Four fire engines and around 25 firefighters were called to a house fire in Scott Road, Edgware.
Part of the ground floor of an end of terrace house was damaged by fire. One woman left the building before the Brigade arrived and was taken to hospital by London Ambulance crews, suffering from smoke inhalation.
The Brigade was called at 1103 and the fire was under control by 1152. Fire crews from Stanmore, Mill Hill and Wembley Stations attended the incident.
The cause of the fire is under investigation.