ATP measurements have been earlier used to study the effect of various nutrients on the growth and multiplication of M. leprae. In a preliminary study, we had observed that glycerol and asparagine stimulated the ATP synthesis by M. leprae but this was marginal and not sustained. We have extended the study to investigate the role of various environmental factors which could affect this ATP synthesis. It has been observed that ATP synthesis was better and sustained for a longer period i.e. upto 2 weeks if the M. leprae were incubated at pH 6-6.5 and at 30-33 degrees C in the modified Dubos and Sauton's media. The pH and temperature above these values were suboptimal. It is concluded that temperature and pH are important factors for maintenance and synthesis of ATP by M. leprae.