This paper presents the main results of full-scale shaking table tests carried out in an experimental project, funded under the auspices of the SERA project H2020-INFRAIA-2016-2017/H2020-INFRAIA-2016-1. The experimental campaign aim is the evaluation of the seismic performance of three-leaf masonry walls with weak lime-mortar joints. These walls are typically made of two outer leaves made of stones/bricks while the middle leaf is made of weak mortar. The outer leaves are usually not connected. The responses of different walls to a selected natural record, applied with increasing intensity, first with the horizontal component only and then with both the horizontal and vertical components, are reported. Following tests on the as-build specimens, additional walls were tested after applying a retrofitting technique designed to increase the strength of the masonry wall. The retrofitted walls were tested with the same input seismic sequence applied to the un-retrofitted walls. The reported results shed light on the detrimental effects of the earthquake vertical component on the response of the considered masonry, as well as on the beneficial effects of the applied retrofitting system.