Functional and radiographic outcomes, in addition to complication and reoperation rates of open curettage and grafting without instrumentation or with intramedullary nailing, in the treatment of simple bone cysts (SBCs) of the humerus were compared. Thirty-seven children [25 males, 12 females; median age=9.5 years (range, 3-17 years)] with humeral SBC were treated with curettage and grafting without instrumentation (group 1, 21 patients) or with intramedullary nailing (group 2, 16 patients). The pathological fracture rate was 85.7% in group 1 and 87.5 in group 2. The follow-up duration ranged from 26 to 85 months. The average last follow-up Musculoskeletal Tumor Society functional scores for groups 1 and 2 were 28.9 and 29.5 (P>0.05). Higher, but statistically insignificant (P>0.05), complete or significant partial radiographic healing rates were achieved in group 2 (100%) compared with group 1 (76.2%). The overall complication rate of the entire study population was 21.6% (19%; 4/21 in group 1; 25%; 4/16 in group 2). The reoperation rates for groups 1 and 2 were 9.5% (2/21; one for partial cyst healing, one for recurrence) and 56.25% (9/16; one for surgical complication, eight for implant removal). Surgical intervention is indicated for selected patients with SBCs. Even though perfect functional results were possible with open curettage and grafting, continuous intramedullary decompression with elastic nails led to a higher radiographic healing rate in the treatment of humeral SBCs. Open curettage and grafting with or without intramedullary nailing was associated with a high number of complications, but the rate of reoperation for complications was very low.