GAS refineries are usually located in remote and non residential areas. For that it takes quite a while to reach to the end users. Moreover, in the peak seasons such as winter, the consumption rate is normally very high. Such circumstances make the supply management to be very complex, particularly for the large and populated cities like Tehran. In order to take a reliable control on the DEMAND and to know how the extraction and/or the production rate can match the consumption rate at different regional places especially those of the rural areas, one should think of an off-side un-classical method. Among these, the Artificial Neural Network, ANN; is one of the most common methods which are currently used for different functional goals. In this research an investigation is carried out for applying ANN method for in-advance forecasting of GAS DEMAND load. The method is based on weather parameters with multilayer back propagation, BP algorithm. Throughout the current work, the effective daily temperature is determined, after which the data of the last days is used for network training. Finally it is shown that up to nearly 93% & 99% of the result is in a good agreement with the real data for daily and monthly GAS load forecasting, respectively. The method however can further be developed for prediction of other necessary information in any industries.