S. Greenhoot Fischer, chairman of the board and prinicpal stockholder of District of Columbia National Bank, signed an agreement yesterday to sell his interest in the bank to John Safer, a prominent Virginia real estate investor.

The value of the transaction was not announced, but at current over-the- counter market prices for D.C. National stock, Fischer's holdings are worth almost $1.2 million.

Safer, a member of the board and chairman of the executive committee of Financial General Bankshares Inc., resigned from those positions yesterday.

Fischer is expected to resign as D.c. National chairman and be succeeded by Safer at the next meeting of the bank's board of directors.

Thomas A. Condit, president of the bank, will remain president of D.C. National, which with assets of $116 million ranks seventh in size among the 17 banks in Washington.

Fischer, 62, who had coronary bypass surgery three months ago, said he had decided, "It's about time to let younger men come in. I'm going to take it a little easier now."

Fischer said he will remain on D.C. National's board of directors and loan committee.

The largest single stockholder in D.C. National, Fischer owned about 15 percent -- approximately 32,000 shares -- of the bank's stock which has traded recently for $35 to $36 a share.

Fischer said his primary objective in finding a buyer for his shares was "to guarantee that D.C. National would continue to be a locally owned independent, community-oriented bank.

"the sale of my stock to Mr. Safer assures this. Neither he nor I have any desire to do anything to change its policies or programs."

The comptroller of the currency must approve Safer's purchase of the stock owned by Fischer.

Safer owns about 1 percent of Financial General but probably will be required to sell those shares because of federal restrictions on interlocking ownership of banks. Because of the pending takeover bid by Middle Eastern investors, Financial General stock is selling at a record price of $23 a share, making Safer's 60,700 shares worth about $1.4 million. CAPTION: Picture, S. GREENHOOT FISCHER . . . 'Time [for] younger men.'