In a survey commissioned by software firm Intervoice, 17% of people said they had stopped banking online while 13% had abandoned web shopping.
Technologies such as online check-out services and credit card readers were pinpointed as potential ID risks.
More than half thought that the government's proposed ID card was the best way to combat identity theft.
Concerns about how secure identity is online have risen following high-profile phishing attacks.
The term refers to the practise of creating look-alike websites, often of banks and other financial institutions, and duping people into visiting them and giving out personal information such as pin numbers and passwords.
Despite online concerns, it is an offline solution that is seen as the best way to tackle identity fraud.
Fifty seven percent saw ID cards as the best way to protect themselves against identity theft.
This surprised George Platt, general manager of Intervoice, which provides voice automation software.
"An identity card doesn't really help the problem of identity theft other than at the point of purchase," he said.
The result could reflect general confusion as to what identity theft is and how best to combat it, he thinks.
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