The present invention relates to novel methods and novel 
solid support materials for the tandem synthesis of two or more different oligonucleotides on the same 
solid support in one synthetic run. The methods involve novel support preparations comprised of two or more types of orthogonally protected anchor groups. Subsequent to the selective removal of the first of the respective protective groups, the first 
oligonucleotide is assembled on the deblocked anchor groups according to 
standard methods, preferably via 
phosphoramidite chemistry. Following the capping of said first 
oligonucleotide, the anchor groups blocked by the second type of protective group are selectively liberated and serve is the starting point for the 
assembly of a second 
oligonucleotide, and so forth. After completion of all of the syntheses on the 
solid support, the oligonucleotides are released from the solid support and deprotected at the nucleobases, using 
standard methods. Preparations obtained using the method of this invention, generally contain two or more different oligonucleotides. Such preparations are particularly useful in applications that require pairs of 
oligonucleotide primers, several probes at a time, duplexed 
nucleic acid fragments, or other combinations of oligonucleotides that are useful in applications such as PCR, sequencing, multiplexed 
genotyping, 
cloning and 
RNA interference. The invention includes procedures for the preparation of the novel solid supports of the invention.