Sergio Tuis attended the Scuola Superiore d'Arte in Milan. He made his comics debut at the art studios of Roy d'Ami in 1956. There, he worked on 'La Pattuglia dei Bufali', a series written by d'Ami and published at the publishing house Audace. For the French market, he drew 'Le Condor du Desert', as well as 'Kirby Flint' in Pistes Sauvages' and several stories for the publishing house Lug ('Guillaume Tell' in Zembla, 'Sadko, Le Prince-Archer' in Rodéo). He also produced 'Battler Britton' and several independent war stories for the British Fleetway agency.
In Italy, he was present in Kolosso with some episodes of 'Slim' and Helga'. He also appeared in Horror, Corriere dei Piccoli, Corriere dei Ragazzi (a.o. 'Agente Senza Nome'), Lanciostory and Il Giornalino in the early 1970s. Tuis then left the comics field for a decade to focus on painting. He returned in 1985 with a comic adaptation of the Disney film 'Return to Oz'. A year later, he joined the publishing house Bonelli, where he has illustrated episodes of 'Martin Mystère', 'Nick Raider' and 'Mister No'.