Following the densification of GPS stations in Antarctica, geodetic observations are playing an increasing role in geodynamics research and the study of the Glacial Isostatic Adjustment (GIA). It is, therefore, of fundamental importance to have a deeper knowledge on the sensitivity of GPS data to motions related to long-term ice mass changes. In order to investigate the geodynamic phenomena in the Northern Victoria Land (NVL), GPS observations were made during the last decade within the VLNDEF (Victoria Land Network for Deformation control) project. The processed data provide a picture of the motions occurring in the NVL, depicting a well defined vertical pattern of deformation. The comparison between geodetic vertical motions and GIA is addressed, showing a good agreement and highlighting the possible use of GPS geodetic constraints in GIA models. In spite of this agreement, the sensitivity of GPS vertical rates to non-GIA vertical motions has to be carefully evaluated.