The peroxisome is a ubiquitous, subcellular organelle participating in a diverse array of metabolic pathways. The peroxisomal membrane and its components play a key role in organelle assembly and functions. Disorders related to peroxisomal membranes are the peroxisome biogenesis disorders and X-linked adrenoleukodystrophy. Identification and functional characterization of these disease genes is proceeding at rapid pace helped immeasurably by work in various yeast model systems. The ultimate goal is to elucidate how the encoded proteins interact to produce apparently normal and functioning peroxisomes. The achievement of this goal will lead to a better understanding of disease pathogenesis and hopefully open therapeutic options.