The aim of this clinical report was to describe a case of complete atrioventricular dissociation in a 9-month-old, male ring-necked pheasant (Phasianus colchicus). The case was incidentally determined during the evaluation of electrocardiograms recorded from pheasants. There were no observed clinical symptoms in the bird before or after the electrocardiogram. The PR interval varied, and there was no association of the P waves and QRS complexes in the electrocardiogram. Although the ventricular rhythm was regular (130 beats/min), atrial rhythm was irregular (approximately 91 beats/min). Pathological examination showed there was left ventricular hypertrophy with degeneration of the mitral valve of the heart and well-marked congestion in the liver and lung.