His work was in the style of the old Italian School, although he also appreciated the greater rigour of modern algebraic geometry.

In a well-known paper (Segre 1955) he proved the following theorem: In a Desarguesian plane of odd order, the ovals are exactly the irreducible conics.

His enormous knowledge of classical algebraic geometry enabled him to identify those results which could be applied to finite spaces.

"[2] In 1938 he lost his professorship at the University of Bologna, as a result of the anti-Jewish laws enacted under Benito Mussolini's government.

He spent the next 8 years in Great Britain (mostly at the University of Manchester),[3] then returned to Italy to resume his academic career.