We performed a double-blind, placebo-controlled study to evaluate the efficacy of low and high dose of intravenous immunoglobulins (IVIG) in relapsing/remitting (RR) multiple sclerosis (MS). Patients (n = 49) with clinical definite RR MS were randomly allocated to three groups and treated with 0.2 g/kg (n = 17) or 0.4 g/kg (n = 15) once a month of IVIG and placebo (n = 17) for 12 months. Clinical data were assessed monthly and magnetic resonance imaging (MRI) was performed every 3 months during the study period. Annual relapse rate (ARR) and change of the mean Expanded Disability Status Scale (EDSS) and Neurological Rating Scale Score (NRSS) from baseline to study conclusion were used as the clinical end-points. For MRI activity total lesion volume on T2-weighted image (T2WI), new lesions and gadolinium (Gd)-enhanced lesions on T1WI were analysed. ARR in both IVIG groups (0.88 for 0.2 g/kg and 0.86 for 0.4 g/kg) was reduced compared with placebo (1.24) during treatment period. Neurological disability measured with EDSS decreased slightly in both the IVIG groups (0.029 and 0.066, respectively) and increased by 0.29 in placebo (P = 0.0117). The neurologic impairment measured by NRSS showed similar trend. The total lesion volume on T2WI increased by 13.56% in placebo whereas in the 0.4 g/kg IVIG group decreased by −3.95% and in the 0.2 g/kg IVIG group increased by 3.6%. The cumulative numbers of Gd-enhancing lesions and new T2WI lesions in the IVIG groups were reduced in comparison with the placebo group. Our findings suggest that the dose 0.2 g/kg of IVIG is equally effective as 0.4 g/kg in reducing MS activity.