  High-resolution spectroscopy and photometric monitoring of the pre-main
sequence star RXJ1608.6-3922 shows that it is not an eclipsing binary, as
previously claimed. Radial velocity measurements covering suitable time spans
in order to detect a spectroscopic binary with the claimed period of about 7
days have been performed. The scatter of the radial velocity does not exceed
2.4 km/s, defining an upper mass limit of 24 Jupiter masses for any eclipsing
companion orbiting this star with the claimed period. Photometric observations
of RXJ1608.6-3922 in 7 consecutive nights (i.e. as long as the claimed orbital
period) reveal brightness variations of the order of 0.2 mag with a period of
3.6 days. The shape of the detected light curve differs from a light curve of
the star recorded in 1996. The small variations of the radial velocity, the
variable shape of the light curve, as well as (B-V) color variations suggest
that the flux of RXJ 1608.6-3922 is modulated by spots on the stellar surface
with a rotational period of 3.6 days. The stellar activity of this star seems
to be highly variable, taking into account the variable shape of the light
curve, with an amplitude varying from 0.5 to 0.2 mag in a few years, as well as
hints for a variable H$_{\alpha}$ equivalent width.
