Inclusion body myositis (IBM) seems to be the most common acquired myopathy among patients of age 50 or over. The characteristic clinical features of IBM include involvement of the quadriceps as well as distal muscles, mainly foot extensors and deep finger flexors. The course of the disease is slow but steadily progressive and most patients after 5 to 10 years require the aid of an assistive device. What distinguishes IBM from other inflammatory myopathies is its resistance to corticosteroids and other immunotherapies. We present a case report, the first in the Polish population, of a male patient with a 10-year history of inclusion body myositis responding well to intravenous immunoglobulin (IVIG) therapy. Despite the almost 10 years duration of the disease, its course was slowly progressive and rather stable. Essential aspects of diagnosis and pathogenesis as well as the therapeutic approach adopted are also discussed.