By mixing normal human fibroblasts with collagen type I + III and taking advantage of the capacity of fibroblasts to contract collagen fibers, it is possible to reconstruct in vitro a simplified equivalent of the human dermis. This tridimensional culture system can be covered by keratinocytes making possible the study of dermoepidermal interactions. In this in vitro model, close to the in vivo situation, the skin cells interact with matrix molecules and are submitted to cell to cell communications. Under the influence of these interactions they differentiate. The predictivity of this tridimensional culture system for studying physiology, pathophysiology and pharmacology is discussed.