The article explores the dynamics between natural gas demand and supply in Italy. The strong increase in natural gas demand since the beginning of the 70s represents a deep transformation of Italy’s energy system which gives rise to security problems. In order to supply Italy with increasing volumes of natural gas, some new pipelines and regasification plants are expected in the next future, but their implementation is uncertain. Thus, there is possibility of natural gas shortage in the future. On the other hand, if all the expected projects will be implemented, situations of oversupply cannot be excluded. In order to study such a problem, a system dynamics model has been built. The model core consists of a stock representing the transport network, with the total natural gas supply acting as inflows, and the total natural gas demand as an outflow. A key role in the model is played by the gas storage system and its capacity to inject or extract natural gas from the network, in order to match supply and demand. The model allows to explore future scenarios, make sensitivity analysis and verify under which conditions a balance between demand and supply exists.