The Finnish tenor, Seppo Juhani Ruohonen, began the training of his voice in Helsinki, and continued his singing studies in Turku, Finland. The he was a student of Luigi Ricci in Rome, of Anton Dermota in Vienna, and finally of Lea Piltti in Helsinki.
Seppo Ruohonen made his debut in 1973 at the National Opera in Helsinki as Alvaro in Verdi's La forza del destino, after he had previously operated as a choral conductor and music teacher. In the following years he had a very successful career as he first lyric-dramatic tenor at the Opera of Helsinki and other Finnish music centers. In the Finnish television, he sang the Duke in a recording of Verdi's Rigoletto. He gave performances and concerts in the Scandinavian countries. Since 1978 he was a member of the Opera of Frankfurt a.M. He was a regular guest at the Deutschen Opernhaus Berlin; and gave guest performances at the Teatro Fenice in Venice, at the State Operas of Berlin and Dresden, Stuttgart and Wiesbaden. At the Opera of San Diego he apoeared as a guest as Riccardo in Verdi's Masked Ball. In 1983 he appeared as a guest with the ensemble of the National Opera of Helsinki at the New York’s Metropolitan Opera in the Finnish operas Die letzten Versuchungen by Kokkonen and Der rote Strich by Sallinen. At the Savonlinna Opera Festival, where he attended almost every year, he sang in 1983 the title role in Verdi's Don Carlos and Erik in The Flying Dutchman. In 1986 he participated as a guest with the Opera North Leeds as Radames in Aida; in 1987 with the Scottish Opera Glasgow as Pinkertion in Madame Butterfly; in 1990 as Enee in Les Troyens by Berlioz; in 1988 at the Staatstheater Darmstadt as Radames.
Highlights of his stage repertoire were the José in Carmen, Hans in The Bartered Bride by Smetana, Faust by Charles Gounod, Cavaradossi in Tosca, Don Ottavio in Don Giovanni and the heroes in the operas of Verdi. He was also a gifted interpreter of contemporary stage and concert works (Inquisitor in Luigi Dallapiccola's Il Prigioniero, 1996 in Tampere), and also a singing teacher.
Recordings: DGG (Die letzten Versuchungen by Kokkonen), BIS (opera scenes by Savonlinna), Finnlevy (operetta recordings).