Peroxisomal disorders are a diverse group of hereditary metabolic diseases that occur as a result of partial or total malfunction of peroxisomes. Peroxisomes are cell organelles that consist of a protein-rich matrix surrounded by a single membrane. They were discovered by Belgian biochemist Christian de Duve in 1965, ten years after he discovered lysosomes. Peroxisomes contain about 50 different matrix enzymes that are essential for various anabolic and catabolic processes. In contrast to lysosomes, which are rich in enzymes that require an acidic environment, peroxisomal enzymes are most efficient in the oxidative surrounding [1, 2]. Peroxisomes are present in the majority of human cells, except in erythrocytes. Depending on the tissue type, their number in a human cell varies from about 100 to 1,000. The largest numbers may be found in hepatocytes and kidney tubular cells, where peroxisomes are involved in the synthesis of bile acids and in detoxification processes (Figure 60.1).