The popular restaurant chain is holding pitches next week to find an agency to work on the 'mystery' brief. It is believed the work may be on the launch of a new menu.
Pizza Express has worked with Frank PR and Stuart Higgins Communications in the past, using both agencies on a project basis.
The news comes amid turbulent times for pizza and pasta restaurants. The economic downturn is encouraging more people to eat at home by buying supermarket pizza or getting takeaways, according to reports.
Delivery services such as Domino's, Pizza Hut and Papa John's are reporting increased sales as cash-strapped consumers order in instead of than eating out.
But the market is still worth more than £1.4bn, with Mintel analysis from last year splitting it £720m from home delivery and £674m from eating in.
Pizza Express recently licensed out its products, allowing them to be sold in supermarkets.
The chain, part of the Gondola Group, is currently the third largest pizza and pasta chain operator in the UK by number of outlets. It trails the market leaders Pizza Hut and Domino's Pizza.
Domino's Pizza has been working with Lexis PR since 2000. Pizza Hut retains Freud Communications. Gondola Group also owns the Ask and Zizzi chains.