The interrelation between chronic stress and multiple sclerosis (MS) has always been known, but the biological foundation for this phenomenon has not yet been proven. Our case-study of 5 patients, both diagnosed with multiple sclerosis and PTSD, attempts to demonstrate various dimensions of interrelation between these two diseases. We have also tried to point out the problems and possible complications doctors might encounter during the treatment of an MS patient who is suffering from chronic stress. Our findings show the need for a multidisciplinary approach in the treatment of patients with chronic PTSD and co morbid multiple sclerosis, which will optimize treatment and result in more cost-effective care. Appropriate identification and optimal pharmacological interventions for both disorders might modify further chronicity of these disorders and thus achieve better outcome.