Modelling in systems biology currently lacks clinical applications. As a possible approach leading to clinical relevance the modelling of tissue homeostasis is proposed. As an example a model of epidermal homeostasis is presented which reproduces central morphological and kinetic characteristics of epidermal tissue. Each individual cell is modelled as an agent. The tissue arises as an emergent phenomenon from the interactions of agents. Each agent's behaviour is qualitatively modelled by a simple differentiation state-flow program. Epithelialisation under the influence of parameters concerning stem-cell location is briefly demonstrated.