EEG and respiration show evident modifications in correspondence with behavioural arousal. For instance, a startle always causes EEG activation and obvious respiratory changes. However, these relationships are poorly studied in non mammalian animals. This report shows the relationships between arousal, respiration and EEG power in reptiles. Twenty /Gallotia galloti/ lizards received chronic electrodes to record EEG and breathing movements. The EEG power was analyzed using FFT analysis during three different states: high arousal caused by gentle manipulation, medium arousal caused by acoustic stimulation and low arousal, recorded during behavioural sleep without sensory stimulation. Irrespective of arousal and respiration, the main fraction of the EEG power spectrum always remained under 4Hz. Highly aroused animals showed polyphasic breathing movements interspersed with short apneic pauses and the EEG power was higher in the 0.5-4Hz range when the EEG recorded during breathing periods was compared with the EEG recorded during apneic pauses. The respiratory pattern showed increased regularity during intermediate and low arousal states, with mono or diphasic movements but apneic pauses were still recorded. The reduction in arousal always paralleled a reduction in EEG power, although the difference between breathing periods and apneic pauses was opposite to the observed during highly aroused states, i.e., the EEG power was increased during apneic pauses in states of medium and low arousal. In conclusion, the respiratory activity causes an increase in the EEG power in highly aroused reptiles and a reduction during states of medium and low arousal.