CIGB-500 is a product whose active pharmaceutical ingredient is GHRP-6, (Growth Hormone Releasing Peptide-6), a synthetic peptide that allows the rescue of cardiac mass affected during Acute Myocardial Infarction. The objective of the study was to determine the toxicity profile of CIGB-500 in dogs. As general methodology, CIGB-500 was administered daily to dogs by intravenous route for 28 consecutive days. All animals were allocated to four groups: Control, Low-Dose (300 μg/kg/day), Mid dose (1000 μg/kg/day) and High-Dose (2000 μg/μg/day). Hypersalivation, hypoactivity, reduced heart rate, changes in respiration, pale gums and erythema of the head region were observed in some animals administered at 1000 and 2000 μg/kg/day. These clinical signs were transient, and were therefore considered non-adverse. Treatment with CIGB-500 did not result in any adverse macroscopic or microscopic changes. A decrease in heart rate value was noted following CIGB-500 treatment at all dose levels an at the end of recovery period, the heart rate effects at 2000 μg/kg/day were comparable to controls. In conclusion, the daily administration of CIGB-500 at doses up to 2000 μg/kg/day was well-tolerated, findings noted were transient, minor, non-adverse and reversible, and the no observable adverse effect level (NOAEL) was considered to be 2000 μg/kg/day.