  Aims. What is the origin of the large-amplitude variability in Wolf-Rayet WN8
stars in general and WR123 in particular? A dedicated spectroscopic campaign
targets the ten-hour period previously found in the high-precision photometric
data obtained by the MOST satellite. Methods. In June-August 2003 we obtained a
series of high signal-to-noise, mid-resolution spectra from several sites in
the {\lambda}{\lambda} 4000 - 6940 A^{\circ} domain. We also followed the star
with occasional broadband (Johnson V) photometry. The acquired spectroscopy
allowed a detailed study of spectral variability on timescales from \sim 5
minutes to months. Results. We find that all observed spectral lines of a given
chemical element tend to show similar variations and that there is a good
correlation between the lines of different elements, without any significant
time delays, save the strong absorption components of the Hei lines, which tend
to vary differently from the emission parts. We find a single sustained
periodicity, P \sim 9.8 h, which is likely related to the relatively stable
pulsations found in MOST photometry obtained one year later. In addition,
seemingly stochastic, large-amplitude variations are also seen in all spectral
lines on timescales of several hours to several days.
