The unfavorable impact of prematurity on the developing cerebellum was recently recognized, but the outcome after impaired cerebellar development as a prematurity-related complication is hitherto not adequately documented. Therefore we compared 31 preterm patients with disrupted cerebellar development to a control group of 31 gender and gestational age matched premature infants with normal cerebellar development. Supratentorial brain injuries during the neonatal period were comparable between the groups. At a minimum age of 24 months motor and mental development was assessed by standardized tests. Disrupted cerebellar development was associated with significantly poorer scores both in the subtests for neuromotor (p < 0.001) and mental development (p < 0.001), respectively. Mixed CP was diagnosed in 48% of affected patients, whereas none of the patients of the control group had mixed CP. Microcephaly and epilepsy were significantly related to disrupted cerebellar development. Preterm patients with disrupted cerebellar development exhibit poorer outcome results in all investigated variables. The role of the cerebellum in neurodevelopment after prematurity seems to be underestimated so far.