The objective of this study was to determine if the presence of micro cysts of Sarcocystis lamacanis in the heart of alpacas (Lama pacos) produced any electrocardiographic changes. Fourteen alpacas were divided into a control group (n = 7) and a group of animals infected (n = 7) with the parasite S lamacanis. Electrocardiograms in non-sedated animals were performed 3 days in a row, by means of a bipolar and unipolar augmented system. Two alpacas were sac-rificed and their hearts sent for histopatho-logical analysis. The electrocardiographic parameters obtained did not differ from the normal parameters found in previous stud-ies. Variable QRS complex morphology, low QRS voltage, and a variable mean electri-cal axis of the frontal plane was found. Histologically, the micro cysts were located in the myocytes and not in the cells of the conduction system. The micro cysts did not appear to cause any kind of alteration in the conduction of the electrical impulse through the myocardium.