The aims of the study were (1) to replicate previous quantitative studies of motor activity in low-risk and high-risk preterm infants and (2) to apply a new method of systematic analysis of the qualitative characteristics of general movements in these two groups of infants. Sequential one-hour videorecordings of the unstimulated infants in the incubator were made during the preterm period and then continued during the postterm period until about 20 weeks. The high-risk group consisted only of infants with signs of haemorrhage and/or leucomalacia in the repeated ultrasonograms of the brain. The neurological follow-up continued up to a minimum of one and a maximum of three years of corrected age. The quantification of the various motor patterns in 12 matched pairs of low-risk and high-risk preterm infants revealed a slight but significant (P = 0.05) excess of isolated arm movements in the low-risk cases during the activity phase. No other movement pattern differed significantly. The qualitative assessment of general movements during the preterm period resulted in all but one of the 14 low-risk cases having a normal quality of general movements. In the lesion-group (N = 29) all the infants had an abnormal quality during the preterm period. Eight cases later became neurologically normal although 1 of them had strabism. In addition, one infant was blind (ROP) and retarded and one other had mental retardation. Nineteen infants later developed cerebral palsy (two monoplegia of a leg, three hemiplegia, 5 diplegia and 9 quadriplegia). Strabism was present in 48.3% of the whole group of 29 cases. A semi-quantitative estimation of various aspects of the abnormal general movements made a typology of abnormal patterns possible. A graphic display of developmental trajectories of individual cases, depicting the course of abnormal aspects along the time axis, helps document the evolution of abnormal signs. Their course is a better predictor of the neurological outcome than the nature and localization of the lesion, detected by imaging techniques. The qualitative assessment of general movements from videorecordings is a reliable, quick, cheap and totally non-intrusive method in neonatology for the early detection of functional impairment of the nervous system.