The aim of this study was to show the role of magnetic resonance imaging (MRI) in elucidating the aetiology, or at least pathogenesis, of cerebral palsy (CP). A systematic review of studies using MRI in children with CP was performed according to pathogenetic patterns characterizing different timing periods of occurence of the lesions, and with respect to gestational age (term vs preterm) and CP subtypes. Out of the studies published since 1990 in English, six met all the inclusion criteria; they involved children with spastic and dyskinetic CP. Abnormal MRI was reported in 334 out of 388 (86%) patients and gave clues to pathogenesis in 83%. Fourteen studies met only part of the inclusion criteria and abnormal MRIs were reported even more frequently in these (91%; 930/1022). Periventricular white matter lesions were most frequent (56%) followed by cortical and deep grey matter lesions (18%); brain maldevelopments were rather rare, described in 9%. Brain maldevelopments and grey matter lesions were more often seen in term than in preterm-born children with CP (brain maldevelopments: 16% vs 2.5%; grey matter lesions: 33% vs 3.5%); periventricular white matter lesions occurred significantly more often in preterm than in term-born children (90% vs 20%). CP is mainly characterized by brain lesions which can be identified by MRI in around 75% of preterm infants; brain maldevelopments occur in around 10%.