The October crop of doings around town:

AUCTION: Oct. 29, sponsored by the Auxiliary of the D.C. Medical Society, to benefit the medical schools at George Washington, Georgetown and Howard universities. Further information: 223-2230.

CONCERT SERIES: The Dumbarton Avenue series begins its sixth season Oct. 5 with a wine-tasting benefit. First concert is Oct. 21. Further information: 965-2000.

COLLOQUIUM: "The Superpowers and the U.N. -- Is Peace Possible?" sponsored by the U.N. Day Committee of Arlington, Oct. 24, at Mount Olivet Methodist Church, Glebe Road and N. 16th Street. Details: 243-1078.

BLOCK PARTY: Cleveland Park holds its 15th annual party Oct. 1 from noon to 7 p.m. It features a raffle, baked goods, games, a silent auction and free entertainment. Location is the Macomb playground, 3400 block of Macomb Street NW. Rain date is Oct. 2.

BAZAARS: A Norwegian one is scheduled Oct. 22, from 10 a.m. to 4:30 p.m., at St. Dunstan's Episcopal Church in McLean. A smorgasbord is the main event. Details: Karen Jameson, 451-4905. The annual Claridge House bazaar is scheduled for the same day, from 10 a.m. to 3 p.m. It features arts and crafts, particularly Christmas decorations. Claridge House is located at 1500 S. Fern St., Arlington.

OKTOBERFEST: Oct. 8, from 10 a.m. to 6 p.m., at St. Charles Morromeo Church, 3304 N. Washington Blvd., Arlington. German food and games for children are featured. Call 527-5500 for further information.

END OF SUMMER SALE: The CARE Collection Thrift Shop is selling art, antiques, furniture and clothing to benefit underprivileged people in 36 countries. The sale is held Wednesdays, Thursdays and Saturdays at 600 New Hampshire Ave. NW.

COPING WITH CANCER: Classes to help family members of patients, sponsored by Washington Adventist Hospital. Class begins Oct. 4. Details: 891-5465.

BALLET FOR CHILDREN: "Americana Suite," danced by the Montgomery Ballet Company at the National Capital Trolley Museum in Wheaton on Oct. 2 at 3 p.m. Details: 384-9797.

CHILDREN'S THEATER: Children's Theatre of Arlington presents "Old King Cole" Oct. 21, 22, 23, 28, 29 and 30 at the Thomas Jefferson Community Theatre. Showtimes and ticket information: 558-2165.

FOOTRACE: "Fun run" to benefit the National Symphony Orchestra, Oct. 23, 8 a.m., beginning at West Potomac Park. Registration information: 785-8100.

ANNIVERSARIES: St. Mark's Catholic Church, 7501 Adelphi Rd., Hyattsville, marks its 25th on Oct. 16 with a 12:45 p.m. mass and a 3-7 p.m. picnic. Further information: Marion Vecchiarelli, 935-5484 or 935-6799. On Oct. 15, the Fairlington community in Arlington celebrates its 40th anniversary with singing, dancing, 1940s music and games for children. Location is 3308 S. Stafford St. Information: Charlotte Staelin, 543-8855.

FESTIVAL: Seventh annual Fairfax City Fall Festival, Oct. 8 from noon to 5 p.m., at Main Street and University Avenue. Arts and crafts featured. Details: 385-7858.

ANTIQUE SHOW: To benefit the Hospice of Charles County. Scheduled Oct. 1 and 2 at the National Guard Armory, La Plata. Admission is $2. Sponsored by the Woman's Club of Southern Maryland. Further information: 301-934-3761.

VOLUNTEERS NEEDED: To staff the Northern Virginia Hotline. Application deadline is Oct. 1. Call 527-4077.

SENIOR OLYMPICS: Fourth annual sports festival for Maryland residents 55 and older will be held Oct. 14 and 15 at Towson State University. For details and registration forms, call 301-383-2100. Registration deadline is Oct. 1.

BENEFIT AUCTION: For Ronald McDonald House, sponsored by the Emerald Society of the D.C. Fire Department, will be held at Gonzaga High School Oct. 22. Officials are in dire need of items to sell. Call Lt. Paul E. Jackson (525-5462 or745-2215) for details.