In order to characterize the spin-reorientation transition (SRT), i. e. the change of the easy axis of the magnetization, of ultrathin Ni/Cu(100)- and Fe/Ni/Cu(100)-films the magnetic domain structure was imaged as a function of the Ni and Fe layer thickness, respectively, by using spin-polarized low energy electron microscopy (SPLEEM) during the film growth in ultrahigh vacuum at 300 K. Whereas the size of the domains at the SRT of Ni/Cu(100) is some micrometers, the domain structure of the Fe/Ni-films breaks up into a pattern of 180 nm wide stripe domains. It was shown that the SRT of both Ni/Cu(100) and Fe/Ni/Cu(100) proceeds via a spiral-like rotation of the magnetization within the domains. A discontinuous SRT via coexisting in-plane and out-of-plane magnetized stripe domains is not observed for the film systems.