Background: Treatment adherence is a primary determinant of the success and effectiveness of healthcare. Lack of adherence can lead to treatment failure and death. Although studies have shown that pharmaceutical intervention can improve drug treatment for patients with chronic diseases, studies on pharmaceutical care are not only inconsistent, they are scarce and limited to developed countries, include few patients, and are not studied in randomized clinical trials. Systemic lupus erythematosus is an autoimmune disease with high hospitalization and case-fatality rates. The adherence rate is low (31.7 %) in this group of patients in Brazil, and drug treatment for the disease is complex. Our objective is to evaluate the effectiveness of pharmaceutical care in drug treatment adherence in patients with systemic lupus erythematosus treated at a rheumatology outpatient clinic in Rio de Janeiro, Brazil. Methods: A randomized clinical trial (pragmatic trial) will be conducted. Adult participants (women) from a public hospital in Rio de Janeiro with a diagnosis of systemic lupus erythematosus will be followed for 12 months. A total of 120 patients will be randomized to two groups: intervention (Dader method for pharmaceutical care) and control (health/dietary counseling and risk reduction). The primary outcome will be drug treatment adherence evaluated by the eight-item Morisky Medication Adherence Scale. Secondary outcomes will be clinical improvement and quality of life. Discussion: Patients with systemic lupus erythematosus present with low treatment adherence, thus justifying the mobilization of human resources to optimize their clinical management. Despite the proven effectiveness of pharmaceutical care for various diseases, there are still no studies evaluating its effectiveness in systemic lupus erythematosus. Our hypothesis is that the intervention will also be effective in this patient group.