JupiterResearch carried out a study of thousands of website users and found that 58% have deleted cookies from their machine, and 39% delete all cookies from their PCs on a monthly basis.
Cookies are small files used by websites to track the behaviour of visitors. They enable organisations to offer the most appropriate products or services the next time a visitor logs onto their site. They are also used to recognise registered website users.
But privacy and security concerns are leading consumers to disable cookies on their browsers or delete them after they have been downloaded, said JupiterResearch.
"Given the number of sites and applications that depend heavily on cookies for accuracy and functionality, the lack of this data represents significant risk for many companies," said Eric Peterson, analyst at JupiterResearch.
"Because personalisation, track-ing and targeting products require cookies to identify web visitors over multiple sessions, the accuracy of these solutions has become highly suspect, especially over longer periods."