At present MPDB contains the description of more than 4000 oligonucleotides having a length between 10 to 100 bases. Information is recorded in the following predefined fields: Tipology, Sequence, Organism, Target Gene, Application, Methods, Technical Data and Bibliography, In the last year we have added new items under the fields ''Applications'' and ''Tipology'', and we have inserted a new field, the ''Methods''. Our modifications consider the recent developments of the molecular biology research, under the field ''Tipology'' we have listed the items ''Probe'' (PB), ''Primer'' (PM), ''Antisense Oligonucleotides'' (AS) and ''Peptide Nucleic Acid'' (PNA).