Background: Hip spica casting regimens for the treatment of femoral shaft fractures in a pediatric population aged 1 to 3 years vary. Patient charts were reviewed to determine if there are any clinical differences between 3 and 4 weeks in an ambulatory single-leg hip spica (SLHS) cast versus 6 to 8 weeks in a standard double-leg, non-weight-bearing hip spica cast. Methods: The medical records of 109 patients with femoral shaft fractures treated with a hip spica casting from January 1, 2008 to December 31, 2011 were examined. After exclusions, 94 patients were eligible for inclusion in the study. Patient records were assessed, noting age, weight, type of cast, time in cast, and complications. All casts were applied by senior pediatric orthopaedic surgeons at a single institution. Results: Two groups were evaluated: 59 patients in the SLHS group and 35 in the double-leg hip spica group. The 2 groups were demographically similar with an average age of 2 years, 70.2% of patients were male, 45.7% were black, and 35.1% were white. The average time to cast removal was 4.1 weeks for the single-leg group and 5.3 weeks for the double-leg group (P < 0.001). Both groups had similar low rates of loss of reduction. The double-leg group had a significantly higher incidence of clinically significant limb-length discrepancy (7/35, 20%), compared with the single-leg group (1/59, 1.7%, P = 0.004). In addition, the double-leg group also had more skin problems (11/35, 31.4%) compared with the single-leg group (6/59, 10.2%, P = 0.013). Seventeen patients in the singleleg group were documented as walking in the cast as compared with no patients in the double-leg group (P < 0.001). Conclusions: Patients treated with a single-leg spica cast for 4 weeks had fewer complications than patients treated in a traditional double-leg cast. Femoral shaft fractures in patients less than 4 years old can be treated in a weight-bearing SLHS casts for approximately 4 weeks with fewer alignment and skin complications.