OBJECTIVE: To investigate the effect of acetic acid shockwave phonophoresis on spur morphology, foot pain, and function in patients with calcaneal spurs. DESIGN: A double-blinded, randomised clinical trial. SETTING: Outpatients physical therapy clinics. PARTICIPANTS: One hundred forty-seven patients with calcaneal spurs, 18-65 years old, were randomly allocated to three equal groups. INTERVENTION: The study group (A) received acetic acid shockwave phonophoresis plus conventional physical therapy. The study group (B) received shockwave therapy plus conventional physical therapy. The control group received conventional physical therapy programme only. Interventions were applied twice a week for 3 weeks. OUTCOME MEASURES: Calcaneal spur width, calcaneal spur length, pain intensity level, pain pressure threshold and foot and ankle ability measure activities of daily living subscale were measured at baseline, after 3 weeks of interventions and after 4 weeks of follow-up with no intervention. RESULTS: Between-group differences were observed for calcaneal spur width and length, pain intensity, pain pressure threshold and function after 3 weeks favouring Group A ( CONCLUSIONS: Acetic acid shockwave phonophoresis combined with exercise clinically and statistically improves calcaneal spur width, length, pain intensity, pain pressure threshold and foot function more than shockwave therapy alone or conventional physical therapy. This method might be considered an effective, feasible, safe, non-invasive and locally applicable treatment for heel spurs.