AIMS: This study aimed to determine the factors associated with positive outcomes from extracorporeal shockwave therapy (ESWT) in patients with chronic Achilles tendinopathy, and to develop and evaluate a simple predictive model for clinical use. METHODS: An observational study was carried out on patients with chronic Achilles tendinopathy, managed through the therapist-led Tendo Achilles Pathway (TAP), who did not respond to physiotherapy and podiatry. Logistic regression was used with potential predictors including age, sex, symptom duration, athletic status, type of onset, use of insoles, bilateral symptoms, body side and symptom location, neovessel presence, and severity measurements (Victoria Institute of Sport Assessment-Achilles (VISA-A) and visual analogue scale (VAS)). RESULTS: The sample (n = 183) were mostly female (60%, 110/182), had a median age of 53 years (IQR 24 to 86), and had experienced symptoms from three months to 14 years, with pain most commonly reported in the tendon body (58%, 105/181). Overall, 30% (19/63) were athletes, 55% (54/99) wore insoles, and 89% (54/61) had insidious onset. The mean baseline VAS and VISA-A scores were 57 (SD 23) and 33 (SD 17), respectively. ESWT led to positive outcomes in 46% and only milder initial symptoms and older age were associated with better outcomes (p < 0.05). CONCLUSION: This study presents an analysis of the rate and determinants of positive outcome at three months following ESWT in patients with Achilles tendinopathy. Age and symptom severity emerged as significant predictors of positive treatment success. Furthermore, we developed a very simple predictive model with potential clinical utility.