Opening of fractures and deformation of rock blocks can lead to potentially hazardous rock failures on coastal cliffs. Here we present a time series of ground deformation measurements within selected tuff blocks located at the Coroglio coastal cliff (Naples) in Italy, over a 4-year period (Dec 2014-Oct 2018). The Coroglio cliff is 140 m high and 250 m wide, and is exposed towards the SW, facing the Pozzuoli Bay (Tyrrhenian Sea). The cliff rockface is represented by fractured welded tuff (Neapolitan Yellow Tuff fm.), and includes several rock fronts exceeding 50 m in height.Measurements were acquired along fractures and stratal discontinuities bounding the selected unstable tuff blocks, in order to assess the pattern and magnitude of block deformations (fracture opening and block rotational and/or traslative movements) and their evolution through time. The monitoring system is composed of 8 crackmeters and 2 tiltmeters equipped with internal thermometers, that have been set with a sampling rate of one measurement each 30 minutes, resulting in 48 measurements per day.