Tabs have been replaced by links directing people to 's news, images and groups searches, and the shopping site Froogle is now also linked on the homepage and the search page.
Sponsored links are no longer highlighted in green but now appear in a column separated from the main search by a line. The aim of the redesign is to provide a clearer look and a faster, simpler search experience.
At the same time the company unveiled Google Personalised Web Search and Google Web Alerts, both debuting on Google Labs, which enable searchers to specify what interests them and to receive customised results based on those interests.
The company said that the site had been tested on sample groups, who were given different designs to try out before giving their feedback to the company.
Larry Page, co-founder and president of products at Google, said: "Today, Google takes the first step in providing personal search results based on users' preferences.
"We can deliver search results tailored to your interests or promptly email you new information on any topic. In addition, Google has a cleaner new interface and easy access to the comprehensive Froogle product search."
The company is widely reported to be preparing for an IPO later this year. While it has dominated the search market over the past few years, with the rise in revenues from sponsored search terms other search engines such as Yahoo! and MSN are taking steps to make their products more competitive.
Google remains the most popular search engine in Europe by some margin, with a unique audience of 55.6m and more than twice the market share of its nearest competitor MSN Search.
While users will have to cope with a new interface, not everything at Google has changed with the company saying that the homepage will still carry what it dubs "Google Doodles" to mark significant dates such as Christmas and Chinese New Year.
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