Linda Field was last seen Tuesday at 18303 Teton in Porter, driving away in a red 1999 Ford Explorer with Texas license plate 2GCDH.
Deputies believe the woman's disappearance poses a credible threat to her health and safety.
Field stands at 5'3", 130 pounds, and has gray hair and blue eyes. She was last seen wearing a pink shirt with flowers, black sweatpants with possible letters "U Love," and sandals.
If you have seen her, call the Montgomery County Sheriff's Office at 936-538-3456.