Abstract Kováts' isothermal retention indices on OV-1 columns are reported for several trimethylsilyl, tert-butyldimethylsilyl, cyclotetramethylene-isopropylsilyl, cyclotetramethylene- tert.-butylsilyl, acetyl and trifluoroacetyl derivatives of thymidine, uridine and 2′-deoxyadenosine, together with a few values for derivatives of 2′-deoxyuridine and adenosine. Retention increments for conversion of O-trimethylsilyl functions to E other functions were found to be reproducible in most cases. Positional differences in the retention increments were observed for conversion to OH in the cases of thymidine, 2′-deoxyuridine and 2′-deoxyadenosine, or to O-trifluoroacetyl groups in the case of thymidine. Positional differences in the increments were also observed in the case of uridine, but were quite variable when unprotected OH groups were present. Uridine derivatives having a 2′-O-trifluoroacetyl group decomposed during gas chromatography. The ability of OV-1 columns to separate isomeric derivatives is also discussed.