Objective To construct a recombinant lactobacillus strain expressing IL-10. Methods A signal peptide sequence (sp) was synthesized and cloned into the integrative plasmid pIlac down-stream of lactose-inducible promoter. The recombined plasmid pIlac-sp-IL10 was then introduced into Lactobacillus casei (L. casei) CECT 5276 by electroporation. PCR with genomic DNA of the recombinant lactobacillus as the template was performed to confirm the integration of IL-10 gene into the chromosome. Western blot was used to detect the expression of the recombinant protein. Results The IL-10 gene had been integrated into the genome of L. casei, and the objective protein was partially secreted into the supernatant. Conclusions IL-10 was expressed by recombinant L. casei CECT 5276.