Earle Palmer Brown, citing philosophical differences, has resigned as advertising agency for The Washington Post. The firm had been The Post's agency for 17 years, primarily handling the newspaper's broadcast advertising.

Jeb Brown, president of the agency, said in an interview that over the past six to 12 months relations between staff members of the two organizations had become "strained."

The relationship will end around the end of the year, Brown said, noting that his firm would continue to handle the account until a new firm is selected. In the meantime, The Post will be contacting other local advertising agencies or area offices of out-of-town ad firms to discuss the account, a Post official said.

"The Post was one of the cornerstones of our agency for many years, and it is very sad to terminate our relationship," Brown said in a prepared statement. "The Post gave us the opportunity to do some very good work, and we appreciate the numerous awards we shared with them."

Brown said that although The Post had been the company's largest client until about 1976, the growth of the firm's business made the loss of The Post account less significant than it might have been in the past. "The Post is not our largest client by a large stretch," Brown said.

A Post official declined to say how many of the company's ad dollars were handled by the Brown agency, one of the area's largest.

Earle Palmer Brown's annual advertising billings have risen from $3 million to $25 million over the past five years, Brown said.