Samuel Bradley was educated at Manchester Royal School of Medicine and qualified MRCS and LSA in 1862. He was later a medical officer with the Cunard Company, a general practitioner at Bowness and also taught physiology at Stonyhurst College. He was also surgeon to the Ancoats and Ardwick Dispensary. In 1865 he was involved in a very public dispute with the Manchester Board of Guardians, accusing them of treating those in their care in a harsh manner. The Poor Law Board investigated his charges, which it upheld.
Bradley lectured at Owens College in anatomy and surgery, and wrote a number of papers on the measurement of crania, mental disease, syphilis, and the evolution of disease. His Manual of comparative anatomy and physiology was first published in 1869. He edited, with Walter Whitehead, Manchester medical and surgical reports in 1870-1, and remained editor after it merged with its counterpart in Liverpool. Bradley was a well-regarded popular lecturer on scientific subjects. He was also known as a brilliant conversationalist and versifier. He died of pneumonia at Ramsgate in 1880.