Sporadic inclusion body myositis has a significant impact on the life of the elderly. Despite some similarities to other myopathies with established genetic defects, little is known about mechanisms of its development and no effective treatment is available. Therefore, there is a need for animal models that can faithfully reconstitute important aspects of this human disease. The authors recently expressed a mutant form of human gelsolin in mice under the control of a muscle-specific promoter. This induced myopathic changes reminiscent of human inclusion body myositis. In this study, immunogold labeling is used to further characterize this model. The study demonstrates a presence of gelsolin amyloid deposits within the rough endoplasmic reticulum. It further compares this mouse model to human sporadic inclusion body myositis.