MPIRICALcorrelationsforthequasi-steadydragcoef!cientofa sphere in compressible ow have been presented by severalauthors (e.g., Henderson [1] and Loth [2]). Such correlations areneeded in numerical simulations of compressible multiphase owsinvolving spherical particles. In this Note, the accuracy of thecorrelationsofHenderson[1]andLoth[2]areassessedusingthedatacollectedbyBaileyandStarr[3],andanimprovedcorrelationforthedrag coef!cient of a sphere in compressible ow is developed. Theimproved correlation is validated for shock-particle interaction,using the recent shock-tube experiments of Jourdan et al. [4].