The primary objective of the study is to evaluate the impact of early treatment with Tysabri in Relapsing Remitting Multiple Sclerosis (RRMS) participants on their quality of life (QoL) as measured by Multiple Sclerosis Impact Scale-29 (MSIS-29) over 2 years. The secondary objectives of the study are: to evaluate the impact of early treatment with Tysabri in RRMS participants over 2 years on the following: annualized relapse rate (ARR), Expanded Disability Status Scale (EDSS), work productivity, quality of life (QoL) by EuroQol 5-Dimension questionnaire (EQ-5D), QoL by Subject Global Assessment of Wellbeing visual analog scale (VAS) and to evaluate clinical disease-free status (relapses, EDSS) over 2 years.