Oxygen abundances in H II regions of eight spiral galaxies are derived through the p-method using published spectrophotometric data (314 spectra of H II regions in eight spiral galaxies). The values of the radial oxygen abundance gradients were determined. The search for a global asymmetry in oxygen abundance distributions over the disks of galaxies was carried out. We do not find a significant signs of global asymmetry with one exception. In the galaxy NGC 2903, a compact area with several H II regions is revealed in which the oxygen abundance is considerably less than the average oxygen abundance for the same distance from the galaxy centre.