Aim: To investigate relationships between hand function, brain lesions, and corticomotor projections in children with unilateral cerebral palsy (CP). Method: The study included 17 children (nine males, eight females; mean age 11.4 [SD 2.4] range 7-16y), with unilateral CP at Gross Motor Function Classification System level I and Manual Ability Classification System level I or II. Hand function was assessed with the Box and Blocks test and Assisting Hand Assessment (AHA). Conventional structural magnetic resonance images were assessed visually for type, location, and extent of brain lesions. Single-pulse transcranial magnetic stimulation (TMS) provided information on organization of corticomotor projections. Results: The most favourable hand function was seen in children who had white-matter damage of immaturity with mild white-matter loss and contralateral motor projections. Children with ipsilateral projections had the most impaired function. Nevertheless, in this subgroup a range of ability was seen (AHA 29-59%). Motor-projection patterns appeared to be influenced by lesion extent and location, but not by lesion type. Interpretation: Combining information from structural magnetic resonance images and TMS can improve prediction of hand function. A wide variation in hand function was seen within all motor-projection patterns. Although the most impaired hand function was seen in the ipsilateral motor-projection group, some children in this group had fairly good ability. Such information is important for treatment planning.