A noted child psychiatrist pleaded not guilty Friday to charges he molested seven boys in his care, and his lawyer said the accusers had mistaken routine physical examinations for sexual abuse.

William Ayres, 75, appeared briefly in San Mateo County Superior Court with his wife and lawyer at his side as a prosecutor added three additional counts involving two new alleged victims to the indictment.

Dozens of Ayres' former patients, dating to the late 1960s, have come forward to accuse him of abusing them, but in many cases the allegations fall outside the statute of limitations.

Ayres now faces 21 counts of lewd and lascivious behavior involving seven former patients. Five of the boys were between 9 and 12 when the alleged abuse took place.

Prosecutor Melissa McKowan wouldn't discuss details of the two new victims. She told the defense lawyer she expected to two more boys to soon be added.

McKowan said many more alleged victims, both within and outside the statute of limitations, are continuing to come forward. At last count, she said there were nearly 40.

Prosecutors say Ayres would get the boys alone in his examination room under the pretense of giving them a physical. He then asked the boys to undress and "examined" their genitals, according to his accusers.

Defense lawyer Doron Weinberg, however, said no abuse took place.

"Dr. Ayres did not molest them," he said outside court. "They were mistaken."

Weinberg cited the case of a Santa Clara County doctor he defended who was charged with sexually assaulting six female patients during pelvic exams. That man's first trial ended in a mistrial and a second, an acquittal.

"You start an idea in people's heads that something they experienced was really improper," Weinberg said. "Memories get adjusted."

Ayres was elected president of the American Academy of Child and Adolescent Psychiatry, serving from 1993 to 1995, and received accolades from county officials for his "tireless effort to improve the lives of children."