  We describe the first results of a programme to obtain rotation curves of z~1
disc galaxies in the near-infrared using the Ha emission line in order to study
the Tully-Fisher relation. To put any observed evolution into perspective and
to investigate any possible selection biases, we constructed a control sample
of low redshift galaxies that had rotation velocities and images available for
measuring their dynamical, photometric, and morphological properties. Compared
to local objects with isophotal sizes similar to the high redshift targets, we
find that our sample of galaxies with spatially resolved rotation curves, the
most distant sample so far (<z>~0.9), clearly reveals a brightening of ~1.1 mag
in the rest-frame B-band. The observed offset can be explained by a combination
of increasing surface brightness, decreasing rotation speeds, and slightly
smaller disc scale lengths of the high redshift galaxies.
