Objective: This study aims to investigate the effectiveness of cognitive group therapy in cognitive components, resilience, self-efficacy and defensive styles of females with multiple sclerosis. Design: This research is a quasi-experimental study with a pretest-posttest control group design accompanied by a two-step follow-up procedure. Of all the patients with multiple sclerosis referring to the MS Society of Khorasan-e- Razavi in 2014, 30 individuals were selected through available sampling method and were randomly assigned to two experimental and control groups. Implementation: The experimental group underwent metacognitive therapy during 8 weeks while the control group followed the ordinary course of the sessions provided by the MS Society. Metacognition questionnaire-30 (MCQ-30), Connor and Davidson Resilience Scale ‎‎(CD-RISC), Sherer General Self-Efficacy Scale and Defense Style Questionnaire (DSQ) were used in the pretest, posttest and follow-ups.‎ Inclusion criteria consisted of the following: The final diagnosis of developing MS by the neurologist, signing a written consent form to participate in the study, having at least a diploma and achieving scores 1 to 4 in EDSS diagnosed by the neurologist. Exclusion criteria were as follows: Receiving psychological treatments at least one month prior to entering the study, a history of metabolic diseases like thyroid and absence of more than two sessions. Interventions: The experimental group underwent metacognitive therapy during 8 weeks while the control group followed the ordinary course of the MS Society sessions. Metacognition questionnaire-30 (MCQ-30), Connor and Davidson Resilience Scale ‎‎(CD-RISC), Sherer General Self-efficacy Scale and Defense Style Questionnaire (DSQ) were applied in the pretest, posttest and follow-ups. The main outcome variables: Cognitive components, resilience, self-efficacy, defensive styles