Currently, six medications are approved by the US FDA for the treatment of relapsing forms of multiple sclerosis (MS). In contrast, no pharmacological agent has proved to be effective in patients with secondary-progressive MS without relapses, or in patients with primary-progressive MS. One of the principal issues concerning an optimal pharmacotherapy for relapsing forms of MS is the optimal time of treatment initiation. There is now an almost universal consensus among MS experts that many patients will benefit from early therapy. However, several formidable challenges exist in identifying individuals who will benefit versus those who will do well without intervention. How do we define early MS and what clinical and paraclinical markers may be useful in defining the timing and nature of therapy? Do patients with a benign form of MS require therapy or are they exposed unnecessarily to adverse effects of our currently available medications? How do we identify disease progression and treatment failures? This review discusses these issues and outlines the evidence for application of 'early' treatment in patients with relapsing forms of MS.