PR professionals now have until Friday, March 4 to submit their entries, due to popular demand.
Entry forms for the league tables include the overall PR Week Top 150 as well as the consumer, healthcare, technology and public sector tables.
Agencies are required to have their submissions signed off by their auditors, and all entries are checked by the PRCA to ensure accuracy.
Last year's Top 150 table was topped by Bell Pottinger Group. Freud Communications came top of the consumer table.