The 2003–04 Serie C1 was the twenty-sixth edition of Serie C1, the third highest league in the Italian football league system.
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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
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Catanzaro and Crotone promoted to Serie B
L'Aquila, Paternò, Taranto and Viterbese relegated to Serie C2
Varese,L'Aquila,Paternò,Viterbese