A 32-year-old otherwise healthy man presented with acute-onset bilateral blepharoptosis of 6 days' duration. On examination, he had severe ptosis bilaterally and mildly restricted abduction in the left eye. Brain magnetic resonance imaging showed a 10-mm-diameter lesion in the dorsal midbrain. The ptosis resolved spontaneously within two weeks. Systemic investigation did not uncover any aetiological factor. During 70 months' follow-up, neither any systemic disease nor ptosis relapse developed. Isolated nuclear midbrain ptosis has been previously reported in a few patients and these had neoplastic or inflammatory causes. In this patient, spontaneous resolution of the nuclear ptosis within weeks suggested that the underlying cause might be isolated ischaemic damage to the central caudal nucleus.