MCI Communications Corp., the Bell System's Washington-based competitor, yesterday reported increased revenues and profits for the year, but decreased earning per share.

Net income rose from $7.1 million to $13.3 million while earnings from operations increased from $30.6 million to $37.2 million. Revenues for the year rose 52 percent from $95.2 million to $144.3 million.

MCI said earnings per share decreased from 23 cents to 20 cents because of dividend requirements on two series of convertible preferred stock issued in December 1978 and last September.

MCI had fourth-quarter revenues of $43.4 million, a 59 percent increase from $27.3 million a year earlier. Net income increased 87 percent to $5.2 million (10 cents) from $2.8 million (6 cents.)

MCI Chairman William G. McGowan said he was satisfied with the company's performance. "First we show an increasing rate of growth in our overall business, and second we are continuing to capture a higher percentage of revenues in pre-tax earnings," he said.

B. F. Saul Real Estate Investment Trust posted its first quarterly profit since December 1974, partly because of a large volume of condominium conversions, the company said.

Cash flow from operations before mortgage principal payments rose to $1.95 million for its second quarter ended March 31 from $47,000 for the same quarter a year ago.

Net income for the quarter was $1.037 million (17 cents a share) compared with a loss of $1.221 million.

"The improvement was due primarily to a large volume of condominium conversions," the company said in a statement. Condominium-conversion profits were $3.3 million for the quarter, up from $646,000.

"This improvement was partly offset by the effects of an increase of an average of 4.7 precentage points in the prime rate to which the trust's bank borrowing are tied, and by the use of relatively-high-cost bank borrowings and senior notes to repay" subordinated notes that matured on Feb. 1, the company said."