Masonry infill walls are widely used as enclosure elements in reinforced concrete (RC) buildings to provide thermal and acoustic insulation. Past earthquakes have identified the out-of-plane collapse of the masonry infill walls as one of the predominant modes of failure. Out-of-plane failure is characterized by brittle behaviour and it is therefore a threat to human safety. Moreover, the out-of-plane capacity may be significantly affected by the presence of cracks due to the in-plane damage related to the interstorey drift. In order to identify the out-of-plane behaviour of infill walls depending on the in-plane damage, an experimental campaign based on cyclic quasi static tests has been initiated on a full-scale infilled RC portal frame at the Laboratory of Structures of the University of Basilicata. The one-bay (4.5m span), one story (3m height) frame infilled with two layers of hollow clay brick walls 8cm and 12cm thick, has been subjected to in-plane loading by means of three reversed cycles for each increasing amplitude, until the story drift was equal to 2% and extensive damage occurred to both the infills and the RC members. After each set of tree in-plane cycles, a dynamic identification of the infills’ layers has been carried out based on ambient vibrations in order to detect changes in its dynamic behaviour. This latter, using sixteen accelerometers placed on the infills’ surface. The identification tests provided valuable information regarding the out-of-plane (OOP) frequencies, vibration modes and damping during the test as function of the in-plane drift. The paper describes the results of the ambient vibration tests and the validation of a finite element model.