At a time when much of America shunned people with H.I.V., Dr. Jerry Rabinowitz welcomed them in.

“He held a lamp up that lit the way for us,” said Michael Kerr, one of the doctor’s patients. “With him, we were safe.”

On Saturday, Dr. Rabinowitz, 66, died along with 10 other people in a massacre at the Tree of Life synagogue in Pittsburgh.

In an era when people complain of rushed doctor visits and too much focus on billable procedures, Dr. Rabinowitz was out of another time, his patients said, a portrait of small-town generosity in a big city. He made house visits, just to talk. When families called the office on Saturday afternoons, Dr. Rabinowitz was there to answer.

He wore a bow tie. He hugged his patients. “Be well my friend,” was how he would say goodbye.

“Family was something that was very important to him,” said Avishai Ostrin, 33, the doctor’s nephew, in an interview from Israel. “And I include in that definition of ‘family’ his patients.”

Dr. Rabinowitz also took risks.

He first saw Mr. Kerr in 1989. It was the early days of the H.I.V. crisis, and people with new diagnoses were frightened, ostracized and writing their own obituaries.

Mr. Kerr, a young graduate student, was among them. Dr. Rabinowitz, he learned, was one of the few doctors in Pittsburgh who could help him.

In his office, Dr. Rabinowitz held Mr. Kerr’s hand. At the time, some practitioners used gloves with H.I.V. patients. Dr. Rabinowitz did not, Mr. Kerr recalled in an interview.

“I was terrified. I lost all my hair,” he said. “He kept me calm.”

Months later, when a despondent Mr. Kerr swallowed a handful of pills, Dr. Rabinowitz came to his side.

“We’ve got to get you past this,” he remembered the doctor telling him. “There’s going to be medications that are going to come your way. So you need to hang in there.”

In 1995, Dr. Rabinowitz helped Mr. Kerr enter a drug trial. He treated him for a total of 25 years, before Mr. Kerr moved to New York. “To him, giving up in that manner wasn’t an option,” said Mr. Kerr, now 54 and a volunteer for the activist group Act Up.

“It was him and Act Up that saved my life. They are the real heroes,” he said.

[Read here for more on the victims of the synagogue shooting.]

Dr. Rabinowitz was born in New Jersey and studied medicine at the University of Pennsylvania, according to his nephew, Mr. Ostrin. He then settled in Pittsburgh, where he opened a small family practice. He is survived by his wife, Miri, his mother, Sally, and his brother, Bill, among other relatives.

Dr. Rabinowitz did not just treat people with H.I.V. He treated everyone and everything: asthma, diabetes, blood clots, lupus. “Because people loved him so much he actually had families with three generations of patients,” Mr. Ostrin said. “Grandparents, parents and children who all went to him.”

Marie Jo Marks, 74, said that Dr. Rabinowitz treated her and her mother for about 30 years.

Until recently, her mother, Helen Nothwang, 102, lived alone in a house about two blocks from the doctor’s office. During the last two years or so, when Ms. Marks would call with information about her mother, Dr. Rabinowitz would pledge to “walk up and see her” whenever his day at the office was over.

“He would take her blood pressure — but he’d basically just sit up there and talk with her,” Ms. Marks said. “And that is something I will never ever forget.”

Dr. Rabinowitz was also a president of his congregation, Dor Hadash, which met in the Tree of Life synagogue, his nephew said.

Mr. Kerr said that after he left Pittsburgh for New York, he thought about writing the doctor a letter to tell him that he had survived — and to thank him. “And I didn’t. I didn’t,” he said. “I thought: ‘Oh I’m just one of many.’”

“He had my back, but I know he had everyone’s backs,” Mr. Kerr added. “And he’s never going to know that I made it.”