The Office of Fair Trading (OFT) has contacted 100 online comparison websites to remind them of the importance of providing clear information.
Research carried out by the body found that some portals could be doing more to improve the level of trust they have with the public.
The main reason that people use such services is to find the best possible deal and the popularity of these sites is set to increase in the future.
Chief executive of the OFT Clive Maxwell said many consumers may not realise how they can get better offers if they are "a bit savvier".
"Not all price comparison websites have the same standards and we are working closely with the government and regulators to ensure that consumers are empowered to make informed choices," he added.
The OFT has released a series of tips designed to show best practice for anyone using a price comparison site.
These include always protecting personal data, using a number of different portals, making the right kind of comparison and doing a bit of research.