"You Don't Know " is a 1961 single by Helen Shapiro. It was written by John Schroeder and Mike Hawker and released on the Columbia (EMI) label in the United Kingdom on 29 June 1961. "You Don't Know" topped the UK Singles Chart for three weeks beginning on 10 August. The single sold over a million copies and earned Shapiro a gold disc.

In Japan, where Shapiro's version also became popular in 1962, the song was covered in Japanese by Mieko Hirota, who had also covered Shapiro's earlier hit "Don't Treat Me Like a Child."

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