The effects of different doses of tylosin on serum cytokine concentrations were investigated in healthy and lipopolysaccharide-treated mice. The mice were divided into seven groups. Lipopolysaccharide (LPS) was injected into the positive control group. The other six groups received three different tylosin doses concurrently without or with LPS: 10 mg/kg, 100 mg/kg, 500 mg/kg, 10 mg/kg + LPS, 100 mg/kg + LPS and 500 mg/kg + LPS. After treatment, serum samples were collected at 0, 1, 2, 3, 6, 12 and 24 hours. Serum tumour necrosis factor alpha (TNFalpha), interleukin 1beta (IL1beta) and IL10 levels were determined by enzyme-linked immunosorbent assay (ELISA). Tylosin doses of 10 and 100 mg/kg induced no cytokine production in the healthy mice. Tylosin at 500 mg/kg had no effect on TNFalpha or IL1beta production, but it induced IL10 production in healthy mice. All doses of tylosin reduced the elevated TNFalpha and IL1beta in LPS-treated mice but increased their IL10 levels. In conclusion, these data suggest that tylosin has an immunomodulatory effect at the dose recommended for use against infection.