Typically, in earthquake engineering practice only saturated fine grained soils such as fine sands are considered liquefiable. Liquefaction of unsaturated sands has, however, been observed in laboratory tests and field [1, 2]. To study boundary value problems involving liquefaction of unsaturated sands, a fully coupled computational procedure is necessary. This presentation will detail an analysis procedure to study the response of level ground unsaturated sand deposits subjected to seismic loading. The analysis procedure is a fully coupled flow-deformation finite element code with solid skeleton displacements, pore water pressure, and pore air pressure as nodal variables. The stress-strain behavior of unsaturated sands is modeled by a coupled hydro-mechanical bounding surface elastoplastic constitutive model [3, 4]. The procedure is first validated using dynamic centrifuge tests and a good agreement between computational simulations and centrifuge test results is observed. A parametric study is then conducted to investigate the effects of initial degree of saturation, relative density, and effective overburden pressure on the seismic response of level ground unsaturated sand deposits. The results of the parametric study show that the thickness of the liquefied layer increases with an increase in degree of saturation. The potential for liquefaction reduced with increases in relative density and effective overburden stress.