  We report multiwavelength observations of the two soft X-ray transients
(SXTs) XTE J1859+226 and XTE J1118+480, which we observed with HST, RXTE and
UKIRT. The two sources exhibited very different behaviour. XTE J1859+226 showed
a thermal-viscous disc instability outburst modified by irradiation. XTE
J1118+480, which we also observed with EUVE since it is located at a very high
galactic latitude and suffers from very low extinction, is much more unusual.
It exhibits i) a low X-ray to optical flux ratio and ii) a strong non-thermal
contribution throughout the spectrum, which is likely to be due to synchrotron
emission. We concentrate here on their evolution in the course of their
outbursts.
