Increased disease resistance through improved general immune capacity would be beneficial for the welfare and productivity of farm animals. Classical swine fever (CSF) is a contagious disease in farm animals. The immunoglobulin G (IgG) blocking percentage of CSF virus (CSFV) in serum is an essential diagnostic parameter in veterinary practice. In addition, lysozymes are a part of the innate immune system. To identify quantitative trait loci (QTL) for IgG blocking percentage of CSFV and lysozyme concentration, IgG blocking percentage and lysozyme concentration in serum were measured in a composite pig population before and after challenge with modified live CSF vaccine. Through genome-wide mapping by MQREML analysis and the SOLAR software, several QTL for the lysozyme concentration and the IgG blocking percentage of CSFV were identified, respectively. Within these QTL regions, some known genes were revealed, and some of them may serve as candidate genes in the pig.