The hydrodynamic force on a sphere in mixed convection flow field for low Reynolds and Grashof numbers is considered. The note discusses the difficulties in obtaining analytical solutions and suggests an approximate expression for the combined force. The expression is compared with numerical results and with asymptotic derivations. Conditions for the validity of the expression and its advantages and drawbacks in comparison with previous results are discussed. (C) 2004 Elsevier Ltd. All rights reserved.