During osteoclast differentiation and resorption, both NF-kappaB and Notch signalling are activated. This study defines the mechanism about the influence of NFkappaB on Notch. To this end, IkappaBalphaM and Wild-type-IkappaBalpha were transfected into RAW 264.7 cells. The number of cells that differentiated into osteoclasts was quantified. The resorption area was measured. NF-kappaB transcriptional activity was determined by EMSA. Hes1, DC-STAMP and MMP-9 mRNA expression levels were determined by RT-PCR. Hes1 protein expression was determined by western blots. ChIP was used to study binding of IkappaBalpha to the Hes1 promoter. NF-kappaB inactivation inhibited the differentiation and resorption ability of osteoclasts. Compared with Wild-type cells, NF-kappaB inactivation resulted in an up-regulation of Hes1 expression, and a down-regulation of DC-STAMP and MMP-9 expression. Moreover, in response to RANKL, NF-kappaB inactivation resulted in a down-regulation of DC-STAMP and MMP-9 expression compared with Wild-type cells. The Hes1 promoter was detected by ChIP using IkappaBalpha antibody. In conclusion, our data suggest IkappaBalpha regulates Hes1-mediated activity in osteoclast differentiation and resorption, which supports a cross-talk between NF-kappaB and Notch in osteoclast activity.