Carboxymethylcellulose (CMC) and hydroxypropylmethylcellulose (HPMC) serve as carriers for growth factors and bone substitutes. Although both carriers are placed into the defect sites, their impacts on bone regeneration are unclear. Herein, we examined whether CMC and HPMC affect the differentiation of bone marrow progenitors into osteoclasts and osteoblasts. We therefore induced osteoclastogenesis and osteoblastogenesis in murine bone marrow progenitors in the presence of CMC and HPMC, respectively. Measures of osteoclastogesis were based on the number and activity of tartrate-resistant acid-phosphatase-positive (TRAP(+)) multinucleated cells and expression of marker genes. Osteoblastogenesis was determined by the number and activity of alkaline-phosphatase-positive (AP(+)) colonies and relevant marker genes. Viability was assessed by colorimetric measurement of formazan formation. We report that CMC at 1% caused a significant reduction in the number and activity of TRAP(+) multinucleated cells. Changes in viability were not responsible for the observed effects. HPMC showed no remarkable impact on osteoclastogenesis; however, the concentration was limited to 0.5% because of the high viscosity. The ability of bone marrow progenitors to form AP(+) colonies was not affected by either of the two carriers. Together, these results suggest that CMC and possibly also HPMC can decrease osteoclastogenesis while osteoblastogenesis remains unchanged in vitro. These observations raise the possibility that these carriers might affect the cellular process of bone regeneration.