Manches & Co is looking to merge with another practice to mark the next phase of its expansion following its take-over in 1994 of London-based Rubinstein Callingham Polden & Gale.
Corporate partner Melvin Pedro said: "A merger would make sense for us because there are definite advantages in having the kind of economies of scale which come with being part of a larger firm."
Simon Walker, also a corporate lawyer with Manches, said the firm was "bursting at the seams". It will shortly be moving into additional space currently sub-let at the firm's headquarters in Aldwych House, central London.
The firm is also building up a network of links with US practices in a bid to grow the business through a system of "quid pro quo referrals".
Manches has expanded via a number of mergers with smaller firms throughout the 1990s. It has made a name for itself in family law, though corporate finance accounts for twice as much of its workload.
Recent City deals to its credit include the merger of CentreGold and Eidos to form a new computer products company, and advising Moss Bros on the purchase of Blazer from Storehouse for £7 million.
Earlier this year, Manches received a boost when it recruited veteran Hammond Suddards City lawyer Andrew Knight, who now heads up its banking department.
Manches' merger with Rubinsteins catapulted it into the Top 100 firms and built on its firmly-established media practice. It currently has about 280 staff in London and 50 in Oxford.