The management of cane supply from growers' fields to the mill involves many stakeholders and many tasks to be carried out along the chain, the successful combination of which impacts on the efficiency and profitability of the mill area. A simulation tool called MAGI has been developed to assist millers and growers in designing and assessing new ways of organising supply management. The issues addressed by MAGI include the restructuring of mill areas (Industrial and agricultural capacities, chain structure), changing delivery allocation rules and season duration, and dividing the mill area according to variations in cane quality. MAGI simulates the mill supply over the season on a weekly basis. It takes into account agricultural and industrial capacities, cane production by homogeneous units at the mill area level, and some mill operating variables such as length of milling season and mill opening and closing dates. Each production unit is characterised by its cane area, cane yield, harvest-transport capacity and sucrose curve obtained from the mill database. Scenarios of supply are compared according to weekly and total sugar production over a season. The impacts of unforeseen events such as delivery failures or mill breakdowns on sugar production can also be assessed. Currently based on the Réunion situation, MAGI will be improved to take into account a wider range of sugar production environments, particularly in South Africa.