Fifteen senators, most of them Republican leaders, received more than $50,000 apiece in speaking fees from special interest groups last year, and dozens of senators accepted free trips to such places as London, Tokyo and Honolulu, according to financial disclosure statements released yesterday.

Sen. Robert J. Dole (R-Kan.), chairman of the Senate Finance Committee, was the leader with more than $134,000 in honoraria during 1982, along with expense-paid trips to Las Vegas, San Francisco, Houston and Key Largo. Dole, who spoke to a number of banking, manufacturing, oil industry and health care groups that have a strong interest in his committee's deliberations, gave $51,000 of his earnings to charity.

The leading speechmaker on the other side of the aisle was Sen. Ernest F. Hollings (D-S.C.), a candidate for president, who earned $92,000 in honoraria last year.

The disclosure statements do not provide a precise picture of wealth, because members report their income and assets within broad ranges, with an open-ended top category of $250,000 and up. But the figures confirm that the Senate remains largely a rich man's club.

Among the wealthiest of the 23 Senate millionaires are Lowell P. Weicker Jr. (R-Conn.), with assets in the range of $7.1 million to more than $17.3 million; Claiborne Pell (D-R.I.), $5.5 million to more than $11.3 million; John C. Danforth (R-Mo.), $4.4 million to more than $9.3 million; John Heinz (R-Pa.), $3.4 million to more than $4.9 million; and Lloyd Bentsen (D-Tex.), $2.4 million to more than $3.9 million.

Edward M. Kennedy (D-Mass.) reported assets ranging from $890,000 to $2 million, but also listed assets in several trust funds--one of which is a blind trust--whose values were not disclosed.

The House, which recently raised members' salaries to $69,800, limits outside earned income to 30 percent of salary. But the Senate, while keeping salaries at $60,662, repealed its cap on outside earnings, despite criticism that such fees allow private interest groups undue influence and access.

Much of the $2.4 million in speaking fees distributed last year went to leading Republicans, some of whom were little known before their party won control of the Senate in 1981.

Sen. Jake Garn (R-Utah), chairman of the Banking Committee, received $76,000 from such groups as the National Association of Mutual Savings Banks and Bank Administration Institute. Garn, who gave $16,000 to charity, took two free trips to London, one as a guest of Government Research Corp. and the other courtesy of Michael Lafferty Publications.

Garn spokesman Bill Hendrix said that the senator tries not to speak before national banking lobbies that have business before the committee. He said Garn "wants to avoid the appearance that he's being plied with these speaking engagements."

Among those who paid to hear Dole were the American Bankers Association, Bank of America, Crocker National Bank, the National Association of Manufacturers, the Chamber of Commerce and the American Petroleum Institute. The Federation of American Hospitals paid for Dole's trip to Las Vegas, while Pizza Hut paid for his trip to San Francisco.

"It's not easy work, going out and speaking as much as he does," said spokesman Walt Riker, adding that the fees are Dole's main source of outside income. "It's a tribute not only to his popularity but to his important responsibilities on the Hill."

Among other Republican chairmen:

* Health subcommittee Chairman David F. Durenberger (R-Minn.) received $59,000 from various groups, including those representing doctors, dentists, psychiatrists and chiropractors. Durenberger and his wife also accepted free trips to Beverly Hills, Palm Springs and the Virgin Islands.

* Commerce Committee Chairman Bob Packwood (R-Ore.) received $52,000 from such groups as the Joint Maritime Congress and the National Cable Television Association. The Port of Portland paid for Packwood to visit Hong Kong, China and Japan for nine days in November.

* Energy Committee Chairman James A. McClure (R-Idaho) received $60,000 from such groups as the Atomic Industrial Forum, the American Mining Congress and the National Forest Products Association.

* Labor Committee Chairman Orrin G. Hatch (R-Utah) received $50,000 in fees, plus a trip with his wife to Marco Island as a guest of the Health Industries Manufacturers Association. The disclosure statement indicated that Marco Island is in North Carolina. Hatch also spent two days in Hilton Head, S.C., paid for by Marriott Corp.

* Budget Committee Chairman Pete V. Domenici (R-N.M.) received $83,450 in speaking fees and gave $27,000 to charity. The U.S. League of Savings Associations paid for Domenici's trip to New Orleans, and American Business Press paid for his visit to Boca Raton, Fla.

Some senators accepted more modest forms of compensation. Brown and Williamson Tobacco Co. took Jesse Helms (R-N.C.), Hollings and his wife and Howell Heflin (D-Ala.) and his wife to the Kentucky Derby last year. Jeremiah Denton (R-Ala.) and four colleagues were guests at the John Gardiner Tennis Ranch in Scottsdale, Ariz.

Strom Thurmond (R-S.C.) and his wife received free lodging at two hotels in his home state and a month's use of a camper provided by the Recreational Vehicle Manufacturers Association.

Other legislators were courted overseas. Charles E. Grassley (R-Iowa) and his wife visited Germany, Austria and Switzerland as a guest of the Heritage Foundation. The Aspen Institute paid for the visit of Paula Hawkins (R-Fla.) to Tokyo in July, and Korean University financed her trip to Korea and Hong Kong in October.

Jennings Randolph (D-W.Va.) and Ted Stevens (R-Alaska) received free trips to Switzerland, while Steve Symms (R-Idaho) and Alfonse M. D'Amato (R-N.Y.) went to Taiwan. The Solar Energy Society paid for Frank H. Murkowski (R-Alaska) and his wife to visit Japan, Korea and Taiwan, and the Japan Institute for Social and Economic Affairs took John C. Danforth (R-Mo.) to Tokyo.

Roger W. Jepsen (R-Iowa) went to Hawaii twice last year--once to Honolulu as the guest of the Independent Bankers Association and once to Maui as the guest of Hardee's.

Among local senators, John W. Warner (R-Va.) reported assets of at least $1.7 million. Warner's outside income included more than $100,000 from the sale of a 186-acre property in Fauquier County, $74,431 from the operation of his Atoka Farm in Middleburg and $45,062 from a business partnership.

Warner, who refused to accept speaking fees, is a director of Pro Football Inc., the corporation that owns the Washington Redskins football team.

By comparison, Paul S. Trible Jr. (R-Va.) reported assets of $55,000 to $115,000, including some timberland in rural Virginia. He received $3,800 in honoraria.

Charles McC. Mathias Jr. (R-Md.), who listed assets ranging from $465,000 to $1.3 million, also received $52,000 in honoraria, much of it from universities and academic groups. Mathias also accepted free trips to Las Vegas, New Orleans and Key Biscayne, and spent four days in the Virgin Islands, a trip paid for by the Chicago Council on Foreign Relations.

Paul S. Sarbanes (D-Md.), who listed his home as his only asset, received $6,300 in speaking fees.