He has been described as "the father of modern academic dermatology" and as "the most influential dermatologist of the last 100 years", in part because he trained so many of the leaders in the field.

At the age of 32, fresh out of training, he became Professor and Chair of Dermatology at the University of Oregon.

In 1966 he and dermatopathologist Wallace H. Clark Jr., together with John Raker and Martin C. Mihm Jr., created the first Pigmented Lesion Clinic in the United States at Massachusetts General Hospital.

Fitzpatrick's group also produced the first systematic study of the early warning signs of melanoma.

[7] His hobby was collecting quotations, of which he had so many that he co-edited a column in The Boston Globe called "Reflection for the Day"[1] in partnership with his wife of nearly 60 years, Beatrice Devaney Fitzpatrick.