Objectives: The purpose of this study was to compare union rates for isolated subtalar arthrodesis with and without the use of bone grafts or bone graft substitutes. Methods: We retrospectively reviewed 135 subtalar fusions with a mean follow-up of 18 ± 14 months. The standard approach was used for all surgeries. Graft materials included β-tricalcium phosphate, demineralized bone matrix, iliac crest autograft and allograft, and allograft cancellous chips. Successful subtalar fusion was determined clinically and radiographically. Results: There was an 88% (37/42) union rate without graft use and an 83% (78/93) union rate with bone graft use. Odds ratio of union for graft versus no graft was 0.703 (95% CI, 0.237-2.08). The average time to union in the graft group was 3 ± 0.73 months and 3 ± 0.86 in the non-graft group, with no statistically significant difference detected (p = 0.56). Conclusion: Graft use did not improve union rates for subtalar arthrodesis.