The program CONTROL is based on metabolic control theory and uses the method developed by Reder (1988). In this theory, two sets of parameters are defined in the vicinity of a steady-state: the elasticity coefficients which describe the local behaviour of the isolated enzymes, and the control coefficients which express the response of the whole metabolic network to perturbations at a given step. The theory shows that relationships exist between the control coefficients (summation relationships or structural relationships) and also between the two types of coefficients (control and elasticity coefficients: connectivity relationships). The program CONTROL is divided into two parts (sub-menus). The first one calculates all the control coefficients (flux and concentrations) of a metabolic network from the elasticity coefficients. Using the second menu, the symbolic relationships are obtained between the control coefficients (summation relationships) and between the control coefficients and the elasticity coefficients (connectivity relationships). These two sub-menus can be applied independently to any metabolic network (to date limited to 19 steps and 19 metabolites).