Temporal processing in French children with dyslexia was evaluated in three tasks: a word identification task requiring implicit temporal processing, and two explicit temporal bisection tasks, one in the auditory and one in the visual modality. Normally developing children matched on chronological age and reading level served as a control group. Children with dyslexia exhibited robust deficits in temporal tasks whether they were explicit or implicit and whether they involved the auditory or the visual modality. First, they presented larger perceptual variability when performing temporal tasks, whereas they showed no such difficulties when performing the same task on a non‐temporal dimension (intensity). This dissociation suggests that their difficulties were specific to temporal processing and could not be attributed to lapses of attention, reduced alertness, faulty anchoring, or overall noisy processing. In the framework of cognitive models of time perception, these data point to a dysfunction of the ‘internal clock’ of dyslexic children. These results are broadly compatible with the recent temporal sampling theory of dyslexia. Temporal processing in French children with dyslexia was evaluated in both explicit and implicit temporal tasks and in auditory and visual modalities. We found a greater variability in time estimation (in all tasks) correlated with a poor phonological awareness and difficulties in word reading. Impaired temporal processing that we attributed to a dysfunction of the “internal clock” in children with dyslexia might be directly related to inefficient temporal sampling and poor extraction of temporal cues, probably at the origin of phonological deficits found in dyslexia.