We review the effects of two transcription factor decoy oligonucleotides on apoptosis of human osteoclasts (OCs). The first decoy molecule was designed to inhibit nuclear factor kappa-B (NF-kappaB) binding to target sequence, the second to increase estrogen receptor (ER) alpha expression. We found that both decoy molecules are potent inducers of apoptosis of human OCs, associated with increase of caspase 3 activity and decrease of interleukin 6 expression. In addition, we provide evidence indicating that these oligonucleotides are active in vivo in inducing OCs apoptosis. Because OCs are essential for skeletal development and remodeling throughout the life of animal and man, the approach described is of potential clinical importance.