A baby car seat rental program begins today at Arlington Hospital in cooperation with the state's new Child Safety Seat Law.

The law, which goes into effect Jan. 1, makes mandatory the use of car seats for children under 4 years old and 40 pounds.

The Arlington Hospital Auxiliary is launching its car seat rental program from 7 to 9 tonight in the hospital's Conference Center with a demonstration of the car seats and a safety film.

Car seats will be will be rented between 6 and 8 p.m. Tuesdays at the Conference Center. One hundred seats for infants up to 20 pounds are available for rental for six months for $6 and a $5 deposit. The deposit will be refunded when the seat is returned. A few seats are available for children from 20 to 40 pounds. Those rent for $5 for one month or less plus a $10 returnable deposit.

Because the Arlington Hospital is delivering more than 100 babies a month, it anticipates that additional rental seats will be required to keep up with the need. Organizations or persons wishing to assist may buy car seats at $25 each. For information, call the Hospital Auxiliary weekdays from 8 a.m. to 4:30 p.m. and Saturdays from 8 a.m. to noon at 558-6401.