The 2003–04 Serie C1 was the twenty-sixth edition of Serie C1, the third highest league in the Italian football league system.
Arezzo and Cesena promoted to Serie B Varese, Pavia and Prato relegated to Serie C2 Repechage : Pavia and Prato admitted at Serie C1 2004–05 Catanzaro and Crotone promoted to Serie B L'Aquila, Paternò, Taranto and Viterbese relegated to Serie C2 Varese, L'Aquila, Paternò, Viterbese