The class II cytokine receptor (CIICR) genes Il10r2 and Ifnar1 are localized on mouse Chr 16 in a cluster that also contains the CIICR genes Ifnar2 and Ifngr2. The structure of the Il10r2 gene was deduced and consisted of 7 exons and 6 introns arrayed in an organization similar to its human ortholog. We also present a revised Il10r2 cDNA sequence with a total of 100 bp of additional nucleotide sequence in the 5' and 3' untranslated regions, and report the first extensive profiles of Il10r2 and Ifnar1 mRNA developmental stage and adult tissue expression. Promoter-luciferase reporter constructs were used to define the major region (-108 to +67) that conferred basal expression of the Il10r2 gene. Long-range comparative genomic sequence analysis between the mouse and the orthologous human CIICR genomic loci revealed several conserved non-coding regions. The most proximal conserved non-coding sequence was a 204-bp element located 1.6 kb upstream of the transcriptional start site of Ifnar2 that had repressor-like activity in transient transfection assays with an SV40 promoter-luciferase reporter construct. The identification of multiple conserved non-coding sequences will provide the basis for further investigations to elucidate CIICR gene regulation.