AIM: This systematic review investigated the availability of assessment tools to evaluate bimanual skills in young children (< or = 3y) with hemiplegic cerebral palsy. Evidence for validity, reliability, and clinical utility of the identified instruments was sought. METHOD: Ten electronic databases and grey literature were searched (earliest 1806) to February 2009 to identify articles that met criteria related to the child's age and diagnosis, and included a discrete bimanual assessment. Further searches for evidence of psychometric properties of each identified assessment were undertaken. For quality criteria, we evaluated the internal validity of each study and appraised the validity and reliability of identified assessments. RESULTS: From 1435 papers retrieved, 15 were eligible for inclusion, and 11 assessments of bimanual performance were identified. Ten assessments had inadequate evidence for reliability and validity. Only the Assisting Hand Assessment had evidence for reliability and validity for its intended purposes. INTERPRETATION: Reliability and validity are fundamental considerations when developing or selecting assessments. Additional considerations for assessing young children include the following: (1) standardized administration and scoring; (2) items that capture the complexity of bimanual behaviour; and (3) protocols and items targeted within a small age range to meet specific developmental needs. A validated assessment of younger infants is needed to support early intervention during this period of rapid brain development.