Although there is some conflict between whether his first successful transfusion occurred in 1818 or 1829, it seems more likely that in 1829 he performed the first successful human to human transfusion. Regardless of the date, it is agreed upon that Dr. Blundell extracted four ounces of blood from the arm of the patient's husband using a syringe, and successfully transfused it into the patient. Over the course of five years, he conducted ten documented blood transfusions, five of which were beneficial to the patients, and published these results. During his life he also devised many instruments for the transfusion of blood, many of which are still in use today.