"One possible explanation is the news coverage about the sort of information companies are able to access as a result of people agreeing to use their apps, social networking sites or websites," Dr Philippa Smith said.
"People may also be getting a sense of that intrusion on their online privacy when they suddenly get an email or a pop-up on their browser selling them something which is close to what they might have been searching or reading about on the internet."
InternetNZ chief executive Jordan Carter said the results gave some important insights and he was pleased that most respondents - around 68 per cent - were active in trying to protect their online privacy.
"This does, however, give us evidence that nearly one third of people may need further education and information about the importance of online privacy," he said.
"This is a key focus area for InternetNZ and something we are working hard on to improve."
Despite the concern, 45 per cent of respondents agreed there was no such thing as privacy online and accepted that fact.
Most felt they had nothing to hide and privacy concerns were exaggerated, while more disagreed than agreed that other internet users were violating their privacy.
Other survey findings provided a picture of how Kiwis are using their time online: nearly all were merely surfing the web, 91 per cent used it for news and 85 per cent were logging on to social media.
The survey also explored respondents' interests in expanding their internet use and found three-quarters were interested in different types of use, including accessing education, more use for entertainment and use of government or council services.
But not all were reaping its benefits and a digital divide still persisted.
"Age and household income still seem to be the biggest barriers to internet usage," Dr Smith said.
The survey, which has been carried out every two years since 2007, is part of an international collaborative project undertaken in 39 countries.
How to keep a low online profile
• Consider how much personal information you give. You have a choice about what information you provide.
• Read website privacy notices. If a website has a privacy notice this may give the purpose for collecting personal information.
• Adjust your browser settings to control the collection of information. Websites can collect information about your browsing habits through the use of cookies.
Source: Office of the New Zealand Privacy Commissioner