MCI Communications Corp. reported record profits and revenues yesterday from what company Chairman William McGowan called the first fiscal year of gains "entirely through . . . day-to-day operations in the telecommunications marketplace."

International Bank of Washington also posted record results for the first quarter of 1979, and B.F. Saul Real Estate Investment Trust reported an improvement.

MCI, a Washington firm that competes with American Telephone & Telegraph Co. in providing intercity communications services to large-volume users, earned $7 million in the year ended March 31 compared with $5.2 million a year earlier (which had included a one-time gain of $1.5 million).

Revenues rose 29 percent to $95 million while earnings per share were 23 cents in both periods, because 8 million common stock equivalents were not included in last year's computation. On a fully diluted basis that accounts for future translation of investments in MCI to common stock, applicable to MCI for the first time, per share earnings were 20 cents in the recent year.

Fourth-quarter revenues jumped 40 percent and earnings rose to $2.8 million from $637,000. McGowan noted that preivous years for MCI included elements of non-recurring revenues. "Now, we are standing entirely on our own ability to sell and to serve the business telecommunications user on a daily basis," he added.

McGowan also revealed that banks that have lent more than $70 million to MCI have agreed to a one-half percentage point interest rate reduction as of May 19

International Bank, a merchant banking and financial services firm, reported record first-quarter profits of $3.7 million (51 cents a share) compared with $3.5 million (49 cents) a year earlier. Revenues rose 13 percent to $5.7 million.

Overseas operations contributed 12 cents a share to the recent quarter's earnings, up from 10 cents, as gains were posted in shipping, foreign insurance and banking line, Chairman George Olmsted said.

Property and casualty insurance profits rose fractionally, life insurance earnings were up 13 percent and investments lin industrial companies contributed 28 cents a share, a gain of 16 percent. Finance and leasing operations reported the first profitable quarter in some time.

B. F. Saul Real Estate Investment Trust, the largest in the Washington area, reported yesterday that a negative cash flow from operations last year has been reversed. In the six months ended March 31, Saul had a positive cash flow of $537,000 compared with a year-earlier deficit of $913,000.

Cash flow from operations reflects income after all expenses other than depreciation and before gains from selling properties. This measurement is used to monitor actual operating results of the trust, which continues to operate with a net loss.

For the recent six months, the loss was $1.96 million compared with $2.85 million a year earlier. Results for the 1979 period include $1.5 million in profits from conversion of a Saul-owned apartment building to condominiums.