The Merced County Sheriff's Office said Keith-Ann Reid left her house near Tyler Road on August 17.
They say Reid suffers from Alzheimer's and also has short-term memory loss. She is known to leave her house and walk around North Merced.
Some people have called in tips saying they've seen Reid in Merced, but deputies have not been able to locate her.
Anyone with information on Reid's whereabouts is asked to contact the Merced County Sheriff's Office at 209-385-7445.