Man-made debris is a global problem for seabirds because it is ingested by many species. Markham’s Storm Petrel Hydrobates markhami, which breeds in the Atacama Desert and is endemic to the Humboldt Current in the eastern South Pacific, has been poorly studied in this regard. Earlier studies found low levels of man-made debris in the species’ diet. We quantified the current frequency-occurrence of manmade debris in fledglings and adults of Markham’s Storm Petrel in Chile. We found that 16 of 25 fledglings and all adults contained manmade debris in their digestive tract, indicating the prevalence of man-made debris in this species’ diet is higher than previously reported. Additional work is needed to assess the importance of this finding to conservation efforts.