Fibromyalgia is a chronic and incapacitating condition that produces, as main symptoms, pain, and stiffness. In addition to these physical symptoms, it is also accompanied by psychological symptoms such as cognitive deficits, anxiety, and depression. One of the non-pharmacological treatments that have been used in this pathology in recent years is neurofeedback. In this study, we analyze the efficacy of sLORETA Neurofeedback in the case of fibromyalgia. The experimental subject was a 37-year-old patient. Quantified electroencephalography studies were applied on three occasions, one initial, another after fifteen days of waiting list, and another after treatment. Psychometric scales were also applied at the same time to evaluate the patient's psychological and physical state. The treatment consisted of 5 sessions of Neurofeedback LORETA in Brodmann area 2. After the treatment, a neurometric, psychometric, and clinical improvement were found. The improvement of the patient after 5 sessions is relevant since previous studies using neurofeedback in fibromyalgia, despite finding positive results, needed a higher number of sessions to achieve relevant results. Therefore, the intervention with neurofeedback LORETA in fibromyalgia patients could be an alternative or complement to current treatments.