We studied the effect of Chrysalin, a synthetic 23 amino acid thrombin precursor, on fracture repair acceleration. This preliminary prospective, double blind, randomized study compared two doses (10ug and 100ug) of Chrysalin to placebo (saline), injected into distal radius fractures in 90 patients. Follow-up was weekly for eight weeks, then three and six months. Safety evaluation included reporting adverse events; efficacy examined blinded radiographic evaluation of healing by treating surgeon (investigator), orthopaedic hand surgeon, and radiologist. No differences in safety parameters were seen. The investigator's evaluation of cortical bridging found significant healing acceleration in the low (10ug) dose of Chrysalin, compared to placebo. Median healing time was 24 days (10ug dose), compared to 31 days (placebo), and 36 days (100ug dose), a statistically significant difference (p-value 0.0067). The radiologist assessed trabecular bridging as significantly accelerated in the 10ug dose (p-value 0.13). Time to event analysis showed Chrysalin-treated fractures healed earlier than placebo; extra-articular fractures healed at 4 weeks as assessed by the investigator (Fisher exact p- 0.039) and the independent hand surgeon (Fisher exact p- 0.014). The results demonstrate safety and efficacy of Chrysalin on accelerated healing of distal radius fractures, and support initiation of a larger multicenter clinical trial.