 After graduation, he was appointed lecturer on anatomy and physiology at Bowdoin Medical College at Concord, New Hampshire, and there he undertook also the editorship of the "New Hampshire Medical Journal" which he conducted successfully for nine years.In 1853, on being called to the chair of physiology and pathology in the New York Medical College, Parker left Concord and established himself in practice in New York City, his confrères in the college being Peaslee and Barker.During the three years that Parker held this professorship he established the "Medical Monthly" (1854), which he continued to edit personally for many years with great ability and success, and was co-editor of "The Journal of Medicine", Concord, in 1850.