South Yorkshire Police are asking for help to find Alan Booker as fears grow for his welfare.
The 75-year-old was last seen at around 10am this morning leaving his home address in the Shiregreen area of the city.
He has not been seen or heard from since, described as "very out of character".
The pensioner was wearing navy blue tracksuit bottoms with white trainers and grey t-shirt. He is believed to be carrying a silver walking stick.
Alan is known to frequent Firth Park and Ecclesfield areas but investigating officers believe he could be using buses to travel elsewhere in the city.
Call 101 quoting incident number 450 of 9 August 2016.