Auxiliary ventilation is used to ventilate dead-ends of the drivages, and the most common method employed is to use auxiliary fans and ducting. In order to provide a safe and comfortable environment, it is necessary to provide sufficient air to the working areas. The optimum design of auxiliary ventilation systems may be difficult owing to the methods used in the design of such systems that require complex calculations. In this study, by evaluating data gathered from Turkish Hardcoal Enterprises, a predictive model of the volume flow rate reaching the end of a leaky ventilation duct for a simple auxiliary ventilation system was developed using multiple regression analysis. The independent variables that enter the regression were chosen as duct diameter, fan flow output, fail operating pressure, frictional pressure drop, duct length, duct resistance, and resistance coefficient of leakage paths. The coefficient of determination (R 2) obtained for the predictive model was 0.931, and the residual analysis indicated that the model was statistically acceptable. Also, by using the two-sample t-test, it was shown that the developed regression model was consistent with the results obtained from another data set not included in the derivation of the presently developed regression model. (c) 2007 Elsevier Ltd. All rights reserved.