In order to evaluate whether hypotonia could be the clinical expression of crossed cerebellar diaschisis (CCD), we studied the occurrence and severity of CCD in two groups of hemiparetic stroke patients presenting either with prolonged muscular flaccidity (PMF, n = 14) or with muscular spasticity (MSp, n = 13) over the affected hemisoma. CCD was more frequent and severe in hypotonic than in spastic patients. Neither the time elapsed from the stroke nor the volume of the lesion was significantly different between patients with PMF and those with MSp. The two groups of patients showed different motor deficit scores, but motor deficit severity and CCD did not correlate. We concluded that the persistence of CCD after stroke may be associated with PMF, emphasizing the link between functional cerebellar impairment and muscular hypotonia.