Background: Systemic lupus erythematosus (SLE) is an episodic, chronic, multisystem, autoimmune disease characterized by a widespread inflammation of blood vessels and connective tissues. There is no cure for lupus, but medical interventions and lifestyle modifications can help control it. The seriousness of SLE can range from mild to life-threatening. Patients with SLE who get proper medical care and education can significantly lower disease activity and improve quality of life. Aim of the study: The aim is to evaluate the effect of self-care instructional guide on disease activity among patients with SLE. Design: Non- Equivalent pretest-posttest time series control group design was used in the study. Setting: The study was conducted at the rheumatology and rehabilitation department in one of Cairo University affiliated hospitals. Sample: A convenient sample of 120 male and female adult conscious patients with SLE who fulfilled the eligibility criteria was recruited. Tools: socio-demographic and medical data questionnaire; the adopted
systemic lupus erythematosus disease activity index (SLEDAI) and lupus patient's self-care knowledge assessment test were used to collect data. Results: 45.0% of the study group and 46.7% of the control group are within age range between 20 < 30 years, 86.7% of the study group and 91.7 % of the control
group were females. As for disease activity index scores; there was a significant statistical difference in SLEDAI between the study and control groups after implementing nursing instructional guide (x2 = 17.0 P = (0.001), also, there were highly statistically significant differences in self-care knowledge scores between the study and control groups at 3rd day and 3rd month after implementing nursing instructional guide (x2 = 91.7 P = 0.0001), (x2= 91.7 P = 0.0001) respectively. Finally, there was a statistically significant negative relation between disease activity index and self-care knowledge (r = -0.12 p = 0.17). Conclusion: The self- care instructional guide had a significant effect on the improvement of patients with SLE self-care knowledge and lowering the disease activity state. Recommendation: regular implementation of instructional guidelines programs for patients with SLE to increase their knowledge and improve their quality of life.