The biological activity of nucleic acid ligand is regulated (i.e. enhanced or inhibited) in vivo to produce a desired biological effect. This is accomplished through the administration of a modulator, or regulator, that changes the binding of the nucleic acid ligand for its target or that degrades or otherwise cleaves, metabolizes or breaks down the nucleic acid ligand while the ligand is still exerting its effect. Modulators of the present invention can be administered in real time as needed based on various factors, including the progress of the patient, as well as the physician's discretion in how to achieve optimal therapy. Thus, this invention provides for the first time a regulatable therapeutic regime in the course of nucleic acid ligand therapy.