Laventhol & Horwath, the nation's eleventh-largest accounting firm, has merged with M.B. Hariton & Co., one of the largest District accounting firms, in an effort to expand its presence in the Washington area.

Laventhol's merger with Hariton is one of four mergers the Philadelphia-based firm completed Sept. 1, all with companies that have a strong real estate practice. Specific terms of the merger were not disclosed by either company.

"We are going to strengthen our practice in all major markets in real estate and will continue doing so for a long period of time to provide top talent and services to our clients in those markets," said Geroge L. Bernstein, chief executive officer of Laventhol, which had two offices in the area before the merger.

The new firm, which will operate under the name Laventhol & Horwath and employ 180 people, including 17 partners, will be the third-largest accounting firm in the Washington area behind Arthur Anderson & Co. and Peat Marwick Mitchell & Co, according to Samuel Mancuso, the former managing partner of Hariton who will be the new firm's administrative partner.

"The principal advantages were the tremendous resources that a firm like Laventhol & Horwath could offer, along with the ability to attract some of the larger clients that we would have been unable to attract," said Mancuso.