A microwave induced plasma emission spectrometer operating at low energy (30 W) and low plasma gas pressure (2.5.10-2 Pa) has been used for the quant. measurement of mol. nitrogen in natural gases. The samples have been introduced into the plasma using a counterflow principle to produce emission spectra of diat. mol. fragments in low excitation states (advantage minimized interferences). The N2 concn. has been detd. by measuring the intensity of the N2-line at 337.13 nm and of the NH-line at 336.03 nm. A linear correlation between concn. and signal intensities has been obtained in the range of 0.00% to 14.24% (vol./vol.).