Electrocardiography is a very useful procedure for examination of cardiac disorders in animals. However, very few electrocardiographic (ECG) studies have been conducted on reptiles. ECG examination was conducted to obtain the baseline values of 14 captive marbled water monitor lizards (Varanus marmoratus) at a wildlife facility. The ECG values of the monitor lizards were compared according to gender (ten male and four female), length (nine small and five large) and weight (nine <2 kg and five 2 kg and above). Results of the study determined that the length of the animal positively affected the QRS segment. Gender and weight have no significant effect on the electrocardiographic parameters of the monitor lizards. The ECG profile obtained in the study can be used as a reference for examination of cardiovascular disorders in marbled water monitor lizards.