More than 90 percent of Chinese are worried their private details may be leaked.
A national survey found that 91.8 percent of respondents were worried private information can too easily be divulged and misused.
And 74 percent went further, saying tougher laws are needed to protect privacy.
The survey, carried out by national newspaper China Youth Daily and the Sina.com website in May, had 4,003 respondents.
Of those 39.8 percent said they regularly received unsolicited calls or text messages from companies trying to sell them something.
Just over 53 percent occasionally received such calls or messages.
Respondents were shocked and upset that the unwelcome callers knew so much about them.
They said some companies not only knew their name, mobile phone number, work unit, income and identification card number, but also their children's birthdays, the direction their apartment faces and the license number and brand of their new car.
At a website, called "Souren" or "personal search," the personal details of 90 million people can be accessed, including phone numbers, addresses and work units.
In its conclusion the survey said government departments were to blame.
"Tempted by personal gain, people and departments with access to this information sell it to commercial entities seeking customers," it said.
During the annual sessions of the National People's Congress last year and this year lawmakers called for enhanced legislation to protect personal information.
NPC deputy Zhang Xuedong said: "We urgently need a personal information protection law."
China began drafting a personal information protection law in 2003, but it has yet to be listed in the NPC's five-year legislation plan.
