John Merrill worked with George Thorn at the Peter Bent Brigham Hospital in Boston to further develop dialysis. In 1954 he collaborated with others for the first kidney transplant from the identical twin of a patient with chronic renal failure due to chronic glomerulonephritis. Prior to this transplantation was reserved for those patients thought to be suffering from acute tubular necrosis as there was a good chance that the native kidneys would recover.