Many studies have shown a high prevalence of discrete neuromotor disturbances in schizophrenic patients. It was hypothesized that these disturbances are lateralized and reflect a neurodevelopmental disorder underlying schizophrenia. A new method for assessing subtle motor dysfunction and hemispheric asymmetries is the registration of hand movements with a digitizing tablet. Using this method, we studied hand-motor dysfunction and its lateralization in schizophrenics, as compared with healthy controls. All subjects (27 schizophrenic patients, 13 of them without neuroleptic medication, the others under neuroleptics; 31 healthy controls) drew super-imposed concentric circles. We computed kinematic parameters reflecting velocity and automatization to quantify neurological soft signs (NSS). The patients had significant impairments of regularity of repetitive hand movements, as compared with the healthy controls (F> or =5.35; p< or =0.024(*)). Comparing differences of left- and right-hand performance between patients and controls, we found longer stroke duration (F=(15,98); p=0.000***) and decreased automatization (F=18,14; p=0.000***), especially on the left side in schizophrenic patients. Measuring hand movements with a digitizing tablet is a sensitive method for assessing subtle motor dysfunction in schizophrenic patients, not reflected in the scores of clinical scales. Our findings show NSS in schizophrenic patients, independently of neuroleptics. Further, the hypothesis of lateralization of cerebral structures generating NSS towards the right hemisphere in schizophrenia is supported.