Whole blood, serum, and feather samples from 29 Humboldt Penguins (Spheniscus humboldti) at the Punta San Juan Marine Protected Area, Peru, were analyzed for 55 toxic and essential elements by using inductively coupled plasma mass spectrometry. Mercury (Hg) was analyzed by cold vapor atomic fluorescence. Maximum Hg concentrations in serum (0.0056 mg/g), whole blood (0.297 mg/kg), and feathers (1.8 mg/kg dry weight) were at levels generally not considered to cause health impairment. Of the elements analyzed, only eight (aluminum, calcium, iron, Hg, potassium, magnesium, sodium, and zinc) were detected in serum. These elements, plus selenium and titanium, were also quantifiable in whole blood. Feather analysis detected quantifiable values for the elements found in serum, plus arsenic, boron, barium, copper, manganese, and titanium. Results indicate this important breeding population of endangered penguins did not appear to be exposed to environmental elemental contaminants at levels detrimental to health and reproductive success. However, identification of measurable concentrations of toxic elements at low levels underscores the need for continued environmental monitoring, particularly in the face of expanding regional human populations and industrial growth. These results provide important reference data for temporospatial monitoring of this and other penguin populations.