We report the first patient with a partial trisomy and a partial monosomy of the long arm of chromosome 4: 46,XY, inv dup(4)(pter-->q32::q32-->q26), del(4)(q32-->qter). The boy died from a complex cardiac defect (monoventricle, monoatrium and truncus arteriosus) in combination with a diaphragmatic hernia. In addition he had preaxial polydactyly of the right hand. We compare the clinical features with data from the literature. The phenotype of the patient mainly resembles that in patients with a terminal deletion 4q32.