A purine deoxyriboside (6-thiopurine-2`-deoxyriboside, dPu-SH) and a pyrimidine deoxyriboside (4-thio-2`-deoxyuridine, dU-SH) were conjugated to bovine serum albumin (BSA) in the way that deoxyribose rings were exposed by linking C-6 of purine ring and C-4 of pyrimidine ring to the protein, respectively. Monoclonal antibodies were produced by using these two conjugates as antigens. Group Ⅰ monoclonal antibodies (1B2, 2A3, 4D4, and 8B6) from dPu-BSA immunized mouse showed affinity for purine deoxyriboside derivatives with substitution on N-1, C-2, and C-6 but showed no affinity for the derivatives with N-7 and C-8 substitution. Group Ⅱ monoclonal antibodies (3A3, 3A5, 6A2, and 9B1) from dU-BSA immunized mouse showed affinity for pyrimidine deoxyribosides with substitution on C-2, C-4, and C-5. None of the antibodies had affinity for base derivatives, deoxyribose, and ribonucleosides. It suggests that these monoclonal antibodies may be useful for the study of mechanisms of DNA damage by facilitating isolation of various deoxyribonucleosides excised from damaged DNA.