The aim of this study was to determine whether receptor activator of nuclear factor NF-kappaB ligand (RANKL), osteoprotegerin (OPG) and a calcium:phosphorus (Ca:P) ratio of 2:1 could affect survival and activation of Muscovy duck osteoclasts (OCs). Bone marrow cells were obtained from 5-day-old Muscovy ducks and cultured with (Group A) No added factors, (B) 30ng/mL soluble RANKL (sRANKL), (C) 30ng/mL sRANKL and 10ng/mL OPG, (D) 10ng/mL OPG, (E) 50ng/mL OPG, (F) 100ng/mL OPG and (G) 30ng/mL sRANKL, 6mmol/L Ca and 3mmol/L P. sRANKL promoted the survival of OCs on day 2, whereas the number of OCs decreased with addition of OPG in a dose-dependent manner. OPG and Ca:P (2:1) both inhibited OC survival induced by RANKL. RANKL stimulated bone resorption by OCs, whereas OPG, but not Ca:P (2:1), inhibited the activity of OCs induced by RANKL. RANKL promotes the survival and activation of OCs from Muscovy ducks, whereas OPG and, to a lesser extent, Ca:P (2:1) reduce the life span and inhibited the activation of OCs induced by RANKL.