[en] From 1973 to 1979, the intensity of emission lines and continuum of HR Del has steadily diminished. High excitation lines have disappeared in 1978. The spectral energy repartition in the continuum remains the same in the spectral range 4000-5000 Angstroem. The strong ultraviolet excess found in the spectral range 3600-3250 Angstroem is confirmed by IUE satellite observations in the ultraviolet. Our observations show an important change in the structure of the [0III] lines 4959 and 5007 Angstroem between 1973 and 1976, the polar components becoming weaker than the equatorial ones. (orig.)