[structure: see text] Nucleoside phosphoramidites bearing a fluorous dimethoxytrityl (FDMT) group were used to synthesize fluorous-tagged oligonucleotides, which were subjected to solid-phase extraction using a pH-stable fluorinated adsorbent. On-column detritylation afforded the purified oligonucleotides. The fluorous affinity purification method offers one-pass loading without ammonia removal, high selectivity for the removal of failure sequences, high recoveries (typically 70-100%), and the ability to purify long oligonucleotides (e.g., 50-100-mers).