This article deals with the evaluation of the atmospheric CH4 and CO2 emission from the widely accepted conventional biogas plants operating in India. CH4 and CO2 are the two major constituents of biogas and also the two important greenhouse gases causing the present global warming. Average CH4 and CO2 emission per plant from the floating gasholder model biogas plants ranged between 73 +/- 8.92 and 742 +/- 81.53 g d(-1) and 159 +/- 17.31 and 1476 +/- 152.63 g d(-1), respectively. Emissions from the fixed dome biogas plants ranged between 93 +/- 20.63 and 288 +/- 46.53 g d(-1) CH4 and 196 +/- 40.90 and 598 +/- 93.70 g d(-1) CO2. The current contribution of greenhouse gases from the installed biogas plants in India toward the annual atmospheric CH4 and CO2 budget is estimated to be approximately 0.143 and 0.306 Tg, respectively.