Fire gases are liberated due to oxidation of coal in scaled off coal mines. Monitoring of fire gases is the main tool for the determination of fire status. On that basis, different fire indices can be determined for examining the extent of fire and for devising efficient combat methods. In Indian coal mines, mine fires have become a very problematic issue, numbering more than 200, both surface and underground. The most important fire-affected coalfields include Jharia, Raniganj, Talcher, Ib-Valley, Chirimiri, Singrauli and Ramgarh. For surface (O/C) fires different detection approaches are in use. The purpose of this paper is to review the existing successful techniques for monitoring the mine fire gases and describe different fire indices such as CO/O-2 deficiency, CO2/O-2 deficiency, C/H ratio, Willet's ratio, etc., for interpretation of status of underground (U/G) sealed off fires. Case studies have been presented for assessing status of fire in the U/G mines of some important Indian coalfields. (c) 2006 Elsevier B.V. All rights reserved.