We evaluated the use of oral fluid as an alternative to serum samples for Classical swine fever virus (CSFV) detection. Individual oral fluid and serum samples were collected at different times post-infection from pigs that were experimentally inoculated with CSFV Alfort 187 strain. We found no evidence of CSFV neutralizing antibodies in swine oral fluid samples under our experimental conditions. In contrast, real-time reverse transcription–polymerase chain reaction could detect CSFV nucleic acid from the oral fluid as early as 8 d postinfection, which also coincided with the time of initial detection in blood samples. The probability of CSFV detection in oral fluid was identical or even higher than in the corresponding blood sample. Our results support the feasibility of using this sampling method for CSFV genome detection, which may represent an additional cost-effective tool for CSF control.