Crystalla Dean, 52, was last seen by her daughter at her home in Longsdale Crescent, Oban, at about 20:00 on Thursday.
She was reported missing the next day after failing to return.
Ms Dean is described as being about 5ft 1in tall, of slim build and has curly dyed-blue hair.
Police said she may have been wearing a red top, jeans and boots.
She has pet dogs and normally walks them in a wooded area known locally as The Witches.
Extensive inquiries involving officers and specialist police resources have already been carried out.
The search was taking place on Saturday and involved Police Scotland's mountain rescue team, the coastguard and the local mountain rescue team.
Police Scotland said the missing woman "has recently been dealing with some personal issues and her family just want to know she is safe and well".
Anyone with information should contact the Oban police office.
A large-scale search, involving mountain rescue and coastguard teams, is being carried out in Argyll for a missing woman.