BACKGROUND: The study of electrocardiographic parameters of buffalo in comparison to other large animals is very scanty. Electrocardiography is a very important tool to diagnose cardiac diseases. In this case, standardization of ECG of each species of animal or even each breed should be carried out. This is due to the fact that ECG parameters are related to many factors such as size, breed, sex, etc. Objectives: In this study, which has been carried out for the first time on Khozestan buffaloes, variable forms of P-waves of this animal was determined. Methods: One hundred buffaloes were divided into two age and two sex groups. In this study a base apex lead was used to record ECG for studying prevalence of different forms of P wave and data analysed using chi- square method. Results: P wave configuration varied from simple positive, notched positive, biphasic or either +/- or -/+. Statistical study showed that +/- form of P wave was significant in two sexes. Concomitant presence of simple positive, notched positive and +/- forms were statistically significant between the two sex groups (p<0.05). Differences of various forms of P wave with or without concomitant presence in age groups were not significant. Conclusions: The findings of this study, like other studies showed that if base- apex lead system is used in buffalo, the frequency of simple positive P wave will be higher compared to its other forms.