Estrone (E1) was bound to bovine serum albumin (BSA) to get a complete antigen (E1-BSA). A monoclonal antibody (McAb) specific for E1 was then produced by cell fusion after BALB/c mouse had been immunized with E1-BSA. Analysis revealed that anti-E1 McAb(E1-McAb) was of the IgG1 type, and its molecular weight was 164 000 datons. The affinity constant of E1-McAb reacting with coated complete antigen was 8.2×10^8L/mol. Biotin-streptavidin complex was used for the determination of E1. The calibration curve of free E1 covered a range of 10～10 000 pg/mL.

Key words: BIOTIN, FOLLICULIM (=ESTRONE), MONOCLONAL ANTIBODY, IMMUNOASSAY