A female reticulated giraffe (Giraffa camelopardalis), 20-month-old, 342 kg, died at Seoul Zoo on January 2, 2009 after a stressful episode of chronic diarrhea. Given the appearances postmortem, it was strongly suspected that the giraffe suffered from malnutrition for a long time. Typical appearances of serous fat atrophy were shown on most fat tissues of body organs such as heart, bone, liver, mesentery and kidney. In this study, the sudden death that had been known as "peracute mortality syndrome" was clearly identified to have resulted from a lack of understanding the Browser's diet and general failure in giraffe husbandry. Individualized care and high quality hay must be provided to compensate higher consumption of metabolic energy and to prevent animal loss in winter season.