Every four years, when the 188 members of the Maryland General Assembly face reelection, some of them do not return. As results of Tuesday's primaries began to sink in yesterday, it was apparent that this year's results are likely to lead to a major reshaping of the legislature in January.

Even some of the winners were shaking their heads in disbelief at the number of their colleagues held in high regard in Annapolis proved to be less honored closer to home.

The most significant losers, in terms of legislative leadership, were Senate minority leader Edward J. Mason (R-Allegeny); Del. Torrey C. Brown (D-Baltimore), chairman of the house environmental matters committee, and Del. Frank M. Conaway, chairman of the black caucus, beaten after an investigation into alleged misuse of insurance funds.

There were others: Verda Welcome, the veteran civil rights leader, ousted after 24 years in Annapolis, the last 20 in the senate; two-term senators Arthur H. Helton (D-Harford) and Robert L. Douglass (D-Baltimore); Del. Steven V. Sklar (D-Baltimore), self-styled leader of the "nonleadership," in the house; Del. Frank C. Robey (D-Baltimore), chairman of a key appropriations subcommittee, and veteran Prince George's politician Francis W. White.

Before the election it already was known that three of the five senate committee chairman would not be back: Sen. Edward T. Conroy died of cancer in May; Sen. Harry J. McGuirk ran unsuccessfully for governor and Sen. J. Joseph Curran Jr. is running for lieutenant governor. Melvin A. Steinberg (D-Baltimore County) is going to challenge James Clark Jr.(D-Howard) for the senate presidency, meaning a fourth change in a committee chairmanship. The fifth chairman, Sen. Laurence Levitan (D-Montgomery), faces a tough general election against state Republican party chairman Allan C. Levey.

"There's going to be a lot of jockeying for position," said Baltimore Sen. Julian L. Lapides, who was elected to a fifth term. "Everybody who is coming back is going to try to move up and the new members will probably be strutty for a few months. It will all work itself out eventually, though."

Four years ago there were 50 new delegates and seven new senators. After the Nov. 2 general election, there probably will be about 40 new house members and at least a dozen new senators.

"It's not so much the numbers that are going to change things, because actually there's going to be less turnover than we had figured," said House Speaker Benjamin L. Cardin. "But the kind of people we lost is going to make the legislature a lot different, especially from the city's point of view."

The Baltimore delegation was prepared for a loss in power because of redistricting, from 11 to nine seats in the senate and from 33 to 27 in the house, but its members were not prepared for the loss of so many experienced members at the polls.

"This is going to force the city to be more cooperative with us and Montgomery," said a Prince George's legislator. "They just don't have the influential people over there that they used to have."

One of the most shocking losses to legislators was Mason's. Although a conservative Republican who disagreed with the Democratic majority frequently, he was held in high regard because of his knowledge of the issues and his abilities as a negotiator.

"He took my name in vain on the floor of the senate more than once," said Cardin. "But he was a fine legislator and a real gentlemen. He will be missed."

Mason will be especially missed by the Republicans. During his eight years in the senate he carved out a conservative coalition that often forced the Democrats to compromise on legislation.

"It's a terrible loss for the party because of the kind of legislator Ed Mason was," said Levey, who had broken the party's unwritten rule against primary participation by supporting Mason publicly. "John Bambacus (who beat Mason) will be a fine legislator. But we've lost a very effective minority leader."

The new minority leader almost certainly will be Mason's closest friend in the legislature, minority whip Edward P. Thomas. That is likely to be the only senate leadership position that will not be contested when the assembly begins in January.

Steinberg, who has been working on a coalition to beat Clark since the session ended in April, got major boosts when Sen. Frank J. Komenda (D-Prince George's) and Del. Kay G. Bienen (D-Prince George's), each of whom faced tough battles, were elected. Their victories mean that Prince George's senate delegation leader Thomas V. Mike Miller can deliver eight votes to Steinberg. Clark also was hurt by Mason's loss because Mason had promised to deliver the Republican votes to him if the Democrats could not choose a president in their caucus.

How the freshman will change Annapolis will not be known until the legislature convenes, but everyone agreed yesterday that redistricting and politics had removed some proved talent.

"Guys like McGuirk, Brown, Robey, Mason, Sklar . . . you're talking about people who read and write," said Del. Timothy F. Maloney (D-Prince George's), who won a second term. "Those kind of people are at a premium in Annapolis. We're not exactly waist-deep in talent. It's a loss, a real loss. For everybody."