Hirshfeld (Hirschfeld, Girshfeld) Isidor (b. 1882, Riga – d. 1965) – dentist.

In 1890, Isidor Hirshfeld emigrated to the United States. By 1916, he was teaching at the New York Institute for Postgraduate Dental Education. From 1915 to 1925, he served as director of the first periodontological clinic at the New York Otolaryngology Hospital. Between 1924–1934 and 1927–1934, he directed similar clinics at Beth Israel Medical Center in Boston and in New York.

In 1928, Hirshfeld founded and became head of the Department of Periodontology at the Columbia University College of Dental Medicine. From 1929 to 1947, he practised at New York–Presbyterian Hospital. In 1941, he was elected president of the American Academy of Periodontology.

Isidor Hirshfeld actively supported fundraising efforts for the advancement of dental care in Israel.