Data acquisition from crystals of an icosahedral virus, cowpea mosaic virus (CPMV), was carried out to 2.8 A resolution under an elevated hydrostatic pressure of 330 MPa. This was the first example of a complex macromolecular assembly to be studied by high-pressure crystallography. The data were obtained from the ESRF ID30 beamline using a quasi-plane wave of ultrashort wavelength with a diamond anvil cell and an imaging-plate detector. The results of the high-pressure data analysis are given and are compared with those obtained under standard conditions, showing that the experimental procedures implemented are very efficient in terms of diffraction information collected per unit volume of crystal. These results suggest that the use of a quasi-parallel synchrotron radiation beam of ultrashort wavelength should also be considered for conventional macromolecular crystallography data collection.