Observations at high spectral and temporal resolution are presented of the dwarf nova EX Dra in outburst .
The disk seen in the He i line reconstructed by Doppler tomography shows a clear two-armed spiral pattern pointing to spiral shocks in the disk .
The Balmer and He ii maps also give evidence for the presence of spirals .
The eclipse as seen in the red continuum indicates a disk radius of 0.31 times the orbital separation , which might be large enough to explain the observed spiral shocks through excitation by the tidal field of the secondary .
The eclipse in the Balmer line profiles , well resolved in our observations , indicates a somewhat smaller disk size ( 0.25 ) .
We discuss the possibility that this is related to an optical depth effect in the lines .