  We report here on multiwavelength observations of the two new soft X-ray
transients (SXTs) XTE J1859+226 and XTE J1118+480, which we observed with
HST/RXTE/UKIRT. For XTE J1118+480 we also used EUVE since it is located at a
very high galactic latitude and suffers from very low extinction. The two
sources exhibited very different behaviour. XTE J1859+226 seems quite normal
and therefore a good object for testing the accretion mechanisms in place
during the outbursts, XTE J1118+480 is much more unusual because it exhibits i)
a low X-ray to optical ratio and ii) a strong non-thermal contribution in the
radio to optical domain, which is likely to be due to synchrotron emission. We
concentrate here on the near-infrared (NIR) and optical observations of these
two systems.
