Three species of Deinotherium sensu stricto (Proboscidea, Deinotheriidae), i.e., excluding Prodeinotherium, generally considered to have nonoverlapping chronostratigraphic distributions, are currently recognized from the Miocene of Europe: Deinotherium levius (late Astaracian/Aragonian, MN7+8), Deinotherium giganteum (type species; Vallesian, MN9–MN10), and Deinotherium proavum (a senior synonym of Deinotherium gigantissimum; Turolian, MN11–MN13). Here we describe a sample of 26 cheek teeth from four roughly coeval localities of Ronda Oest de Sabadell (ROS), in the Vallès-Penedès Basin, northeastern Iberian Peninsula, dated to the latest Vallesian (∼9.4–9.1 Ma, MN10) on biostratigraphic grounds. The remains from ROS-D3 represent all the permanent upper and lower dentition and can be unambiguously assigned to D. proavum, the largest deinothere from Europe, based on their large size (well above the range of D. giganteum). Remains from the other localities (ROS-D2, ROS-D5, and ROS-D8) are smaller and generally overlap in size with both D. proavum and D. giganteum. However, an assignment to the former species is more likely given that these species are not known to co-occur and that their dental size ranges were already known to overlap partially. The remains of D. proavum from ROS represent the oldest record of this species, the occurrence of which in the late Vallesian had already been recorded in the slightly younger (∼9.1 Ma) locality of Sinap 49, Turkey. Given that D. proavum is recorded before the Vallesian/Turolian boundary, and that smaller individuals of this species overlap in size with D. giganteum from the Vallesian, caution is required when making biostratigraphic correlations based on late Miocene deinothere remains from Europe.