- A program of treatment for children with diabetes begins at SickKids shortly after Dr. Frederick Banting and Dr. Charles Best of the University of Toronto announced their discovery of insulin. Banting joined the Staff at SickKids in 1923 and was placed "In Charge of Diabetes". Working together with Dr. Gladys Boyd, their program resulted in a 50 per cent decrease in the childhood mortality record from diabetes, as listed over a 10 year period.
- Dr. William Gallie develops living tissue sutures.
- Dr. Frederick Banting, along with Dr. Charles Best, discovers insulin. Banting served his internship at SickKids in 1919 and later became attending physician for diabetic cases.
- Dr. Lawrence Bruce Robertson becomes a pioneer in blood transfusions for children.
- First research laboratory set up at SickKids.
- Well-Baby Clinics are established, most in church basements.
- A tuberculosis pavilion is established. SickKids is one of the first institutions to recognize the value of sunlight in the treatment of TB.
- Pasteurization of milk begins at SickKids, 30 years before it becomes mandatory, due to the successful lobbying of paediatrician-in-chief Alan Brown. Advocacy for children continues today: explaining the dangers of second-hand smoke, cautioning against scalds, and lobbying for bike helmet legislation.
- Visiting Nurse service is established. Nurses visit discharged patients to ensure they receive proper care.