The decadeoxynucleotides, d-T-C-G-G-T-A-G-C-G-C and d-T-G-G-C-G-C-G-T-A-G, corresponding to the nucleotide sequence 51 to 70 of one of the strands, and d-[ 14C]A-C-C-G-A-C-T-A-C-G, corresponding to the nucleotide sequence 56 to 65 of the complementary strand of the gene for the major alanine tRNA from yeast have been synthesized. The synthesis of the decanucleotide, d-T-C-G-G-T-A-G-C-G-C, started with the condensation of 5′- O-monomethoxytrityldeoxythymidine, d-MMTr-T, with 3′- O-acetyl- N (6)-anisoyldeoxycytidine 5′-phosphate (d-pC An- OAc) to give d-MMTr-TpC An. Successive condensations with d-pG 1B- OiB, d-pG 1B- OiB, d-pTpA BZpG 1B- OAc and d-pC AnpG 1BpC An- OAc followed by removal of the protecting groups produced the decanucleotide. The synthesis of the decanucleotide, d-[ 14C]A-C-C-G-A-C-T-A-C-G, started with the condensation of 5′- O-monomethoxytrityl- N (6)-benzoyl-[8- 14C]deoxyadenosine (d-MMTr-[ 14C]A BZ) with 3′- O-acetyl- N (6)-anisoyldeoxycytidine 5′-phosphate to give d-MMTr-[ 14C]A BZpC An. Successive condensations with d-pC AnpG 1B- OAc, d-pA BZpC An- OAc, d-pTpA Bz- OAc and d-pC AnpG 1B- OAc, followed by the removal of the protecting groups, produced the decanucleotide. The synthesis of the decanucleotide, d-T-G-G-C-G-C-G-T-A-G, started with the condensation of 5′- O-monomethoxytrityldeoxythymidine, d-MMTr-T, with N,3′- O-di-isobutyryldeoxyguanosine 5′-phosphate, d-pG 1B- OiB, to give d-MMTr-TpG 1B. Successive condensations with d-pG 1B- OiB, d-pC An- OAc, d-pG 1B- OiB,d-pC AnpG 1B- OiB and d-pTpA BZpG 1B- OAc produced the decanucleotide. The condensing agent used throughout was mesitylenesulfonyl chloride. Isolation of the fully protected oligonucleotide products after every condensation was accomplished by using solvent extraction procedures and/or anion exchange chromatography. The fully deprotected products, d-T-C-G-G-T-A-G-C-G-C, d-[ 14C]A-C-C-G-A-C-T-A-C-G, and d-T-G-G-C-G-C-G-T-A-G, were further purified by anion-exchange chromatography on a DEAE-cellulose columns in the presence of 7 M-urea and were characterized by enzymic degradation to the constituent nucleosides and nucleotides.