Dr. Alan J. Ross, co-owner of a Gaithersburg medical clinic, was found guilty yesterday of assaulting two abortion protesters April 20, one near his home and one near his clinic. Montgomery County District Court Judge Thomas Lohm fined the physician $150 plus $60 in court costs.

The assault and battery charges were placed against Ross by Dennis Burdick and Donna Boccabella, who work with the Pro-Life Non-Violent Action Project, a Gaithersburg group that says it has 1,000 members.

Burdick has been "picketing outside Ross' clinic and praying outside his home for two years," said John Cavenaugh O'Keefe, publicity director for the Human Life Institute, an antiabortion group. He said that Burdick and another antiabortion activist were in front of Ross' home at about 8 a.m. April 20 when Burdick was assaulted.

Boccabella, an Olney resident, was demonstrating outside Ross' clinic when the doctor "punched" her, O'Keefe said. Ross could not be reached for comment.

It was the physician's second assault conviction in three months. On May 13, he was found guilty of assaulting antiabortion activist John F. DeLozier with a hypodermic syringe in January outside the Gaithersburg clinic. Ross was convicted in that case on a charge of carrying a deadly weapon with intent to injure. Sentencing is scheduled for Monday.