Recent studies in stabilished ZrO2 single crystals reveal that oxygen vacancies and/or their complexes are involved in the luminescent process . Samples of rare earth doped zirconia fibres were pulled by the laser-heated pedestal growth (LHPG) method and their photo-luminescence was observed. We report the systematic study of the photoluminescence measured in several samples: ZrO2: Er3+, ZrO2: Er3+: Pr3+: Y3+, and ZrO2: Pr3+: Y3+. The experiments were carried out by pumping the samples with single and multiple UV lines of a Kr+ ion laser (337.5-356.4 nm). Emission spectrum broadening of Er3+ and Pr3+ has been observed and a reproducible strong changes in the luminescence behaviour occurs when the excitation power surpasses a certain value.