In 1828 Andral was appointed professor of hygiene, and in 1839 succeeded François-Joseph-Victor Broussais (1772-1838) as chairman of general pathology and therapy, a position he held for 27 years. In 1823 he became a member of the Académie Nationale de Médecine.
Andral is remembered for his pioneer investigations of blood chemistry. He is considered to be the founder of scientific hematology, and is credited with its integration into clinical and analytical medicine. With his colleague, Louis Denis Jules Gavarret (1809–1890), he performed extensive studies of blood composition. They demonstrated that blood composition varies in different pathological conditions, and their findings showed the importance of blood chemistry as a means of confirming diagnoses.
Andral's crowning written achievement was Clinique médicale, a five-volume work that discussed almost every facet of medicine known at the time. It was an exhaustive summary of French medicine and its development in the early part of the 19th century.
Andral is credited as the first physician to describe lymphangitis carcinomatosa, a disease that is usually associated with cancers of the lung, breast, stomach, and cervix. His father, Guillaume Andral, was also a physician of note.