Complement factor I (IF) reference typing has been examined using polyacrylamide gel isoelectric focusing followed by electroblotting with enzyme immunoassay. The submitted samples could be classified into three common and two new variants, and these were controlled by two common and two rare alleles. Two common alleles were IF*B (the most common allele) and IF*A, and two new rare alleles were designated IF*A1 and IF*B1, respectively.