Holmgren was born in
Östergötland, Sweden, where his father Anders was rector for the Motala-Vinnerstad parish. One of twelve siblings he studied at Linköping before going to Uppsala in 1850. From 1852 he served as a medical practitioner including during the
cholera pandemic in
Norrköping and
Söderköping. He graduated as a Medical Doctor from
Uppsala University in 1861. He went to Vienna and studied under
Ernst Wilhelm von Brücke who sent him to work with
Carl Ludwig at Leipzig. He joined the faculty of Uppsala University and in 1864, was appointed professor of physiology, the first in Sweden. He researched color blindness and his most notable work was about color blindness in relation to rail and sea transport. His research in 1869-70 took him to
London,
Berlin (
Emil du Bois-Reymond), Heidelberg (
Hermann von Helmholtz),
Vienna and
Paris (with
Claude Bernard). Du Bois-Reymond inspired his work on attaching electrodes to the back and front of the eye of frogs to examine retinal responses. He devised a standardized test, now known as
Holmgren's wool test, for color blindness testing in 1874. Following a
railway crash at Lagerlunda in 1875, he advocated the need to preclude people with defective color vision from railway employment. This established the now standard practice of excluded color blind individuals from employment in certain sectors.{{cite web|url= https://sok.riksarkivet.se/sbl/Presentation.aspx?id=13748|title= A Frithiof Holmgren|publisher =Svenskt biografiskt lexikon ==Personal life==