in the earthquake resistant design of buildings, it is necessary to know a priori the value of the ductility that these will be able to reach when they are affected by strong ground motions. these values are available in the seismic design codes, but their estimation can be also made by using expert？s opinion or the actual response of the buildings during seismic events. nevertheless,the problem has been generally centred on the response of structures with ductile behaviour, like special moment-resisting frames, and there are not enough data available on the response of buildings with restricted ductility, such as framed buildings with flat beams and buildings with waffle slabs. therefore, in this study, the nonlinear behaviour of buildings with restricted ductility is examined. in this paper two restricted ductility buildings have been designed according to the requirements of the ehe instruction and of the ncse-02 code. the values of theirs ductility have been thus calculated and compared with the values of the reduction factors applied in the determination of the seismic design forces and with the values of the structural overstrength. additionally, the response of the buildings, designed with steel of different ductilities and yield stress, are studied. finally, the responses of the buildings with restricted ductility are compared with that of a moment-resisting framed buildings designed according to ehe and aci codes.