The Mass General Hospital Blood Draw Lab - Saturday - Hospital Main Campus is open to Mass General Brigham patients with an open laboratory order from their Mass General Brigham provider. No appointment is necessary, walk-in appointments are available. Walk-in appointments are welcome Monday through Friday from 10:00 am to 4:00 pm and Saturday from 8:15 am to 4:15 pm. The blood draw lab is closed on Sundays and holidays. Patients 16 years old and older may receive blood draw services. Patients 13 and older may receive nonblood specimen services. On weekdays, please check in at Wang 221 first, and on weekends check in at Wang 516 directly.