This work tests the hypothesis that the cerebellum is critical to the perception of the timing of sensory events. Auditory tasks were used to assess two types of timing in a group of patients with a stereotyped specific degeneration of the cerebellum: the analysis of single time intervals requiring absolute measurements of time, and the holistic analysis of rhythmic patterns based on relative measures of time using an underlying regular beat. The data support a specific role for the cerebellum only in the absolute timing of single subsecond intervals but not in the relative timing of rhythmic sequences with a regular beat. The findings support the existence of a stopwatch-like cerebellar timing mechanism for absolute intervals that is distinct from mechanisms for entrainment with a regular beat.