The objective of this pilot study was to investigate the feasibility of constraint-induced movement therapy (CIMT) in children with obstetric brachial plexus palsy and receive preliminary information about functional improvements. Two patients (age 12 years) with obstetric brachial plexus palsy were included for a 126-h home-based CIMT intervention (3 and 4.5 weeks) and weekly monitored with the Melbourne Assessment of Unilateral Upper Limb function and the Nine-hole Peg Test. The Assisted Hand Assessment was performed 3 weeks before the beginning of intervention, preintervention, postintervention, and at 3 weeks follow-up (ABA single-case design). Tests were analyzed descriptively, visually, and where possible, using a time series analysis with C statistic. Results revealed changes of arm function in both patients between preintervention and follow-up test as follows: Assisted Hand Assessment from 85 to 92% in patient A and 80 to 89% in patient B, in the Melbourne Assessment of Unilateral Upper Limb function from 87 to 90% (C=0.578, z=1.876, P less than 0.05) in patient A and 72 to 80% (C=0.827, z=2.68, P less than 0.005) in patient B. There was no improvement in the Nine-hole Peg Test in both patients. Improvements as a result of CIMT found in this pilot study may not be considered substantial. However, they justify further research as some findings indicate relationship to the CIMT intervention in the "B" phase. To enhance motivation and to plan a controlled, randomized clinical trial, child friendly applications of the CIMT concept and adequate measures to monitor compliance are being discussed.