The radial scale length of the exponential component of the disc of the Milky Way has been determined in the near infrared .
We have used the TMGS ( Two Micron Galactic Survey ) database which contains positions and K-magnitudes of about 700.000 stars distributed in serveral regions along the galactic plane .
From those we have selected areas more than 5 ^ { \circ } off the plane to minimize the effect of extinction and the contributions of the young disc ; and with longitudes ranging from 30 ^ { \circ } to 70 ^ { \circ } , to avoid contaminations from the central bulge , the bar and the molecular ring , in the inner end , and from the local arm , the warp and the truncation of the disc , in the outer end .
We observed stars with magnitude 9 \leq m _ { K } \leq 10 .
The use of the NIR K-band also reduces the effect of extinction .
In the observation region , m _ { K } = 9.5 ~ { } \mbox { mag } stars are K2-K5 III stars , with an absolute magnitude that is nearly constant , which also greatly simplifies the problem .
We have obtained the value 2.1 \pm 0.3 ~ { } \mbox { kpc } for the radial scale length , which is a typical value when compared with external galaxies of similar types .