Linda P. Barnes, 66, a Capitol Hill real estate broker and neighborhood activist, died of respiratory failure Feb. 21 at her home in Washington. She had complications from treatment for lung cancer.

Mrs. Barnes was active in the Capitol Hill real estate community for 25 years. For 16 years, she was a partner with John P. Janke in the operation of Barbara Held/City Sites Real Estate, which specialized in residential real estate on Capitol Hill.

They started the business, known as City Sites real estate, in 1980, then later acquired Barbara Held Real Estate, which had been one of the pioneering firms in the residential housing restoration movement on Capitol Hill. They sold the business in 1996 to Weichert real estate, where Mrs. Barnes was a property manager for an additional two years.

As a sales agent early in her career, Mrs. Barnes was known for an imaginative and enthusiastic advertising style. In a promotional brochure for a house near Lincoln Park, she described a back yard looking out on an alley and a collection of garages and carriage houses as having a "Parisian-style view."

Mrs. Barnes was a former president of the Capitol Hill Brokers Council and CHAMPS, the Capitol Hill Association of Merchants and Professionals. In 2002, she received the Capitol Hill Community Achievement Award, given by the Capitol Hill Community Foundation. She served on the foundation's board.

In the late 1990s, Mrs. Barnes assisted in the administration and management of Through the Grapevine, a Capitol Hill flower business.

Linda Peterson was a native of Bridgeport, Conn., and a 1962 English literature graduate of Smith College in Northampton, Mass.

She was a high school English teacher briefly in Holyoke, Mass., before moving to Washington in 1963 when her husband, Bart Barnes, joined the news staff of The Washington Post.

The next year, Mrs. Barnes participated in an experimental program at the National Institutes of Health in which women were treated with a fertility drug, Pergonal, which had a propensity to cause multiple births.

She became pregnant with quintuplets but miscarried 20 weeks into the pregnancy. None of the fetuses, three girls and two boys, survived.

Mrs. Barnes continued the Pergonal treatments at NIH, resulting in two more pregnancies, a daughter born in 1966, and twin sons, born in 1968.

She was a member of St. Mark's Episcopal Church on Capitol Hill, where she had been a member of the vestry, a senior warden, a teacher of religious education classes for children and adults, and co-director of the Christian Education program and the worship committee.

After her lung cancer was diagnosed in 2001, she had more than five years of chemotherapy, radiation therapy and various surgeries, including major thoracic surgery that resulted in the removal of substantial portions of her right lung.

Her cancer went into remission, but her respiratory system was so impaired that she was subject to increasingly frequent and lengthy stays at Georgetown University Hospital for treatment of pneumonia and other lung infections.

She addressed several classes of Georgetown University medical students on the emotional impacts of long-term and chronic illnesses on patients and their families, and she discussed ways to cope with those conditions.

Mrs. Barnes paid careful attention to good looks and grooming, habits she maintained in Georgetown's intensive care unit. She arranged with one of the nurses to have her hair washed and blow-dried using a device normally used to fill patients' air mattresses.

Survivors include her husband of 45 years, of Washington; three children, Kate Barnes of Kensington, David Barnes of Brownsburg, Ind., and Michael Barnes of Washington; her father, John H. Peterson of Clearwater, Fla.; a sister, Susan M. Palmore of Washington and Chapel Hill, N.C.; and eight grandchildren.