A 62-year-old disabled woman needed hospital treatment after being pulled from her mobility scooter. The incident happened as she travelled along Pleasant Avenue, Great Houghton, near Barnsley, at 1235 GMT on Monday.
Police say a man approached the victim and attempted to snatch her handbag from the basket on the front of her scooter.
The woman was pulled to the ground when she grabbed the thief's arm, who escaped with the bag containing �70.
She suffered bruising to her lower back and was taken to Mexborough Montague Hospital.
Her attacker was seen hanging around outside the post office in Rotherham Road 20 minutes before the incident.
He is believed to be aged 20 to 28, had a missing tooth, and was wearing a cream coloured bobble hat, blue checked shirt with black, blue and red jeans.
Police say the woman was left shocked and frightened by the incident and are appealing for witnesses.