BACKGROUND: Due to its high prevalence in dual-task paradigms, freezing of gait in Parkinson's disease is thought to be associated with dysexecutive syndrome and attentional disorders. However, the role of specific attentional disorders in patients with freezing of gait is still unclear. OBJECTIVE: Here, we sought to specifically determine which basic attentional modalities are impaired in patients with freezing of gait. METHODS: Seventy-eight parkinsonian patients performed a computer-controlled reaction-time paradigm designed to measure the different attentional subcomponents, controlled for visuospatial processing and motor participation. RESULTS: The freezer (n = 42) and non-freezer (n = 36) groups were matched for age, educational level, MMSE and Mattis Dementia Rating Scale. There were no intergroup differences in simple reaction times, whereas choice reaction times were higher in the freezer group than in the non-freezer group for divided attention (p = 0.023). CONCLUSIONS: At equivalent levels of overall cognitive efficiency, freezer patients showed a greater slowdown than non-freezer patients with a specific impairment in divided attention.