Hadron spectra in high-energypp,pAandAAcollisions are analyzed in a pQCD parton model, including initialkTand its broadening via initial multiple scattering. Within this model the hadron spectra in bothppandpAorAAcollisions can be described very well forpT>2&hthinsp;GeV/c.The modification of the spectra inpAandAAas compared to that inppcollisions is consistent with multiple parton scattering scenario. Such an analysis will shed new light on the physics one can extract from the single inclusive hadron spectra, e.g., freeze-out temperature and flow velocity in a thermal fire-ball model, and parton energy loss in dense matter. ©1999 American Institute of Physics.