Background/Purpose: At our institution, procedures were developed to enlarge and stabilize the thoracic cavity of children born with severe-enough abnormalities of the thoracic cage as to result in lack of normal lung growth and function. In addition to the device known as the vertical expandable prosthetic titanium rib (VEPTR), some type of patch material was needed to cover large congenital defects of the chest cage owing to rib absence or to cover defects created because of the expansion process. Initially, synthetic material, polytetrafluorethylen e (Gore-Tex, WL Gore and Associates, Flagstaff, Ariz) was used, but this proved itself to be restrictive over time and required removal. Thus, a nonsynthetic biodegradable patch material was adopted for coverage of the defects (Surgisis, Cook, Bloomington, Ind)-. Methods: From October 2001 thro- ugh October 2004, 26 growing children undergoing thoracic cage reconstruction received the biodegradable extracellular matrix patch derived from porcine SIS (Cook). A patch was deemed necessary if any one of the following conditions was obtained: (a) herniation of the lung was likely; (b) chest wall musculature was significantly diminished; (c) injury to the lung was likely at reoperation; (d) the defect was greater than 2 ×2 cm. Results: During the follow-up period, 41 months thus far, each of the 26 children has undergone routine, scheduled expansions or change-out procedures every 6 months. The SIS has not required removal for any reason and has not restricted growth of the thoracic cage. Conclusions: Compared with synthetic soft tissue patch material, the nonsynthetic, biodegradable soft tissue patch (SIS) has proven to be a superior alternative, thus far, to others for use in our population of patients for reconstruction of the thoracic cage in the growing child. Background / Purpose: At our institution, procedures were developed to enlarge and stabilize the thoracic cavity of children born with severe-enough abnormalities of the thoracic cage as to result in lack of normal lung growth and function. In addition to the device known as the vertical expandable prosthetic titanium rib (VEPTR), some type of patch material was needed to cover large congenital defects of the chest cage due to rib absence or to cover defects created of of the expansion process. Initially, synthetic material, polytetrafluorethylen e (Gore- Tex, WL Gore and Associates, Flagstaff, Ariz) was used, but this proved itself to be restrictive over time and required removal. Thus, a nonsynthetic biodegradable patch material was taken for coverage of the defects (Surgisis, Cook, Bloomington, Ind) -. Methods: From October 2001 thro- ugh October 2004, 26 growing children undergoing thoracic cage reconstruction received the biodegradable extracellular matrix patch derived from A patch was deemed necessary any one of the following conditions was obtained: (a) herniation of the lung was likely; (b) chest wall musculature was significantly diminished; (c) injury to the lung was likely Results: During the follow-up period, 41 months thus far, each of the 26 children has undergone routine, scheduled expansions or change-out procedures every 6 months. The SIS has not required removal for any reason and has not restricted growth of the thoracic cage. Conclusions: Compared with synthetic soft tissue patch material, the nonsynthetic, biodegradable soft tissue patch (SIS) has proven to be a superior alternative, thus far, to others for use in our population of patients for reconstruction of the thoracic cage in the growing child.