Officials of the Small Business Administration said yesterday that the agency expects to lose some $375 million over the next four or five years as a result of defaults in its Small Business Investment Company program.

The estimate is higher than any previously cited by the agency, but lower than those used by some of the agency's critics. It includes some $200 million that the agency expects to lose as a result of SBICs that have already been placed in liquidation. The remainder is an estimate of the losses that may result from future defaults in the agency's current $1.2 billion investment in SBICs now in good standing.

SBA Administrator Susan Engeleiter and her top aides provided the figures in answer to questions yesterday from Chairman John J. LaFalce (D-N.Y.) of the House Small Business Committee. However, LaFalce's demand to know "the bottom line" for the program produced several minutes of stumbling, during which Engeleiter and her staff could not agree on a figure and then could not explain how they arrived at the one they finally produced.

The uncertainty disturbed LaFalce, who noted that "there are striking similarities in kind if not degree" between the SBIC situation and the savings and loan crisis.

SBICs are companies that combine private capital and government-guaranteed borrowing to raise capital for small businesses and start-up companies that could not obtain financing through conventional channels. The program has been in existence since 1958 and over the years has had some spectacular successes. In the late 1980s, however, the number of SBIC failures turned sharply up, raising question in Congress and elsewhere about the program's management. To cope with the situation, Engeleiter in recent months has reshuffled the program's staff and proposed tighter regulations.