Abstract During myogenesis, the intermediate filament proteins vimentin and desmin are differentially expressed. While desmin levels increase dramatically, vimentin mRNA levels decrease substantially. Here, we show that transfected whole- and mini-vimentin-coding genes ( Vim) are expressed in fibroblasts (mouse L cells) and down-regulated during muscle cell differentiation in culture. Functional assays with 5 ' -end Vim ::cat constructs demonstrate that this repression is controlled by a 5′-element (nt −321 to −160). This region is distinct from Vim promoter elements (nt −160 to + 71) which do not contribute to vimentin's down-regulation during myogenesis.