DIBB Lupton Alsop has lost two leading professional negligence partners to rivals Hammond Suddards.
David Simon, a partner at Dibbs' Leeds office for 22 years, and Manchester partner Brian McKendry have resigned and are thought to be taking their assistants with them.
This is the latest in a number of partner defections from the firm this year.
Last week The Lawyer revealed that Dibbs' head of IT, David Barrett, was joining US firm Arnold & Porter.
Confirming the moves, Hammonds' senior partner John Heller said: "We are very pleased as they have a very good reputation."
A departure date for Simon has not yet been agreed.
Dibbs' managing partner Nigel Knowles was unavailable for comment.