Insurers lack the initiative or ability to compile accurate information about visitors to their websites, finds a survey by WebProbe.
It says 80% of website browsers are men, and three in five are aged under 35 and earning salaries above £20,000.
It also revealed one-in-three respondents visited insurance websites during working hours.
Ken Tipton, chief executive of WebProbe, said: “Insurance companies will struggle to generate profitable revenue from their online facilities until they understand who their customers are and market their services effectively.”
But Justin Skinner, marketing manager at Direct Line which receives more than 200,000 requests for web-based insurance quotes per month, questioned WebProbe's survey results.
He said: “We know more about our customer base than this research suggests otherwise, we would not be as successful as we are.”