  Light curves of the semi-detached eclipsing binary system TZ Eridani in the
Geneva 7-colour photometric system were analysed using the Wilson-Devinney
programme. The physical and orbital parameters have been determined through a
self-consistent simultaneous solution of the seven light curves and of the
radial velocity curves of both components. The following absolute elements of
the components are, for the primary (mass gainer), M_1 = 1.97 +- 0.06 Msol, R_1
= 1.69 +- 0.03 Rsol, Mbol_1 = 2.36 +- 0.09, Teff_1 = 7770 +- 100 K, and for the
secondary (mass loser), M_2 = 0.37 +- 0.01 Msol, R_2 = 2.60 +- 0.04 Rsol,
Mbol_2 = 3.74 +- 0.13, Teff_2 = 4570 +- 100 K. The semi-major axis A of the
relative orbit is 10.57 +- 0.16 Rsol. The regular increase of the period is
described. The spectral type of the components are A5/6 V (primary) and K0/1
III. The secondary has exhibited a long-term luminosity increase of about 0.06
in V between Dec 1983 and Dec 1996. The distance to TZ Eri is evaluated to 270
+- 12 pc.
