The Mass General Hospital Blood Draw Lab - Chelsea is open to Mass General Brigham patients with an open laboratory order from their Mass General Brigham provider. No laboratory appointments are required for blood draws. The blood draw lab is open Monday through Thursday from 8:00 am to 7:00 pm, Friday from 8:00 am to 5:00 pm, Saturday from 8:00 am to 3:30 pm, and Sunday from 10:00 am to 3:00 pm. The blood draw lab is closed on holidays.