Double trisomy mosaicism of two different cell lines is extremely rare, particularly those that involve constitutional trisomy 8. We report a case of 47,XXX/47,XX,+8 in a 12-year-old female presenting with several skeletal anomalies. She exhibited distinct phenotypic features such as tall stature, deviation of the left middle finger, webbing of both thumbs and flexion deformities of the both third and fifth distal intermediate phalanges. A mild impulse-control disorder was observed, without mental retardation. Chromosomal and fluorescence in situ hybridization analysis demonstrated double trisomy mosaicism both on lymphocytes and buccal epithelial cells.