Objective: This paper has the purpose to analyze prospectively the treatment results in patients with chronic plantar fasciitis resistant to conservative treatment who underwent extracorporeal shock wave therapy (ESWT). Methods: We evaluated 30 patients (36 feet); 16 (53.3%) patients were male and 14 (47.7%) female with mean age of 48.7 y.o., varying from 33 to 78 y.o.; 16 (53.3%) present the problem on the left side, 14 (46.7%) on the right ones and 6 (20%) bilateral; the symptomatology varied from 6 to 60 months, with the average of 13.58 months. These patients were submitted to a weekly ESWT session for 4 consecutive weeks. We measured the plantar fascia thickness millimeters with ultrasound and we applied American Orthopaedic Foot and Ankle Society (AOFAS) scale for ankle and hindfoot, and Roles & Maudsley scales in pre ESWT, after one, three and six months after and decrease in the plantar fascia thickness by the ultrasound (p = 0.011) along the different moments studied. Results: We observed improvement of the evaluated criteria (p < 0.001) and plantar fascia thickness by ultrasound (p = 0.011) at different time points studied. Conclusion: The ESWT can be considered an important tool in the primary or adjuvant treatment of the chronic plantar fasciitis when associated with conventional therapies. This methodology is safe, non-invasive and provides precocious rehabilitation and return to regular activities considering the results of the statistical analysis. This resource provides decrease in the thickness of the plantar fascia.