A score and more of Washington-based jazz musicians will double as Santa's helpers this season in providing toys for patients in Children's Hospital who won't be home with their families on Christmas. The Ibex Club, at Georgia and Missouri avenues, will host a jazz marathon this Thursday through Sunday evenings, with proceeds going to buy gifts for the hospitalized youngsters. Patrons of the four-day event can contribute toys of their own choosing if they wish.

"We try to give each of the kids four or five gifts over the course of the day," commented Al Lawson, director of development of Children's Hospital, "and everybody gets into the act -- doctors, nurses, relatives and, of course, Santa himself."

Taking their turns on the bandstand during the course of this "First Annual D.C. Jazz Christmas" will be bassists Keter Betts, Tommy Cecil and Ephraim Woolfolk, drummer Hugh Walker, pianists Wade Beach and Marc Cohen, saxophonists Mickey Fields and Buck Hill, trumpeter Keith Holmes, vocalists Shirley Fields and Ronnie Wells, the Ron Elliston Trio and others, including anticipated sit-ins by jazz luminaries visiting the area this week.

"It's our way of saying to these kids that some of us out here are thinking about you," said club promoter Richard Spring.