Background: Chronic plantar heel pain (CPHP) is a common condition with high prevalence rates and a projected cost of treatment of US$192 to US$376 million. There are several therapeutic approaches and there is increased interest in treatments aimed at the regeneration of tissues with poor healing potential. Our purpose was to investigate the effectiveness of ultrasound-guided percutaneous needle electrolysis in chronic plantar heel pain. Methods: A total of 73 patients with a clinical and ultrasonographic diagnosis of plantar heel pain unrelated to systemic inflammatory disease who had not received any other treatment in the previous 6 months on the affected foot were randomly allocated to receive either ultrasound-guided percutaneous needle electrolysis of the fascia (experimental group, n = 39) or placebo puncture (control group, n = 34). The primary outcome was pain scored with an 11-point numeric pain rating scale (0 = no pain, 10 = maximum pain). Secondary outcomes were function and disability measured by the 21-item activities of daily living subscale of the Foot and Ankle Ability Measure questionnaire, and fascia thickness measured by ultrasound. Outcomes were measured at 1, 12, and 24 weeks. Results: The mixed-model analysis of covariance observed significant group x time interactions from all variables: pain in numeric pain rating scale ( P < .001), FAAM Activities of Daily Living Subscale scale ( P < .002), and ultrasonographic measures of the plantar heel ( P < .002). Patients in the experimental group had better results posttreatment at 12 and 24 weeks compared with the control group. Conclusion: With chronic plantar heel pain, ultrasound-guided percutaneous needle electrolysis improved pain and function. This treatment may also decrease fascia thickness. Level of Evidence: Level I, randomized controlled trial.