Although the therapy of juvenile bone cysts has changed from extensive surgical procedures to less invasive techniques, the curretage of a cyst with subsequent filling of the residual cavity still remains the method of choice in our patients. Instead of autogenous cancellous bone grafts or allogenic grafts predominantly used for this procedure, the bioactive glass-ceramic material BAS-O can recommended, particularly when the cavity to be filled is located in the metyphysis of a long bone (in the region subject to great compression).