X-linked adrenoleukodystrophy (X-ALD) is the most common human peroxisomal disorder, and is caused by mutations in the peroxisomal transmembrane ALD protein (ALDP, ABCD1). The biochemical defect associated with X-ALD is an accumulation of very long-chain fatty acids (VLCFA, e.g. C24:0 and C26:0), which has been shown to result in the accumulation of C26:0-lysophosphatidylcholine (C26:0-LPC).We describe the analysis of C26:0-LPC in dried-blood spots (DBS) using a rapid (30 min) and simple extraction procedure, isocratic HPLC resolution of LPC, and structure-specific analysis via negative ion mode tandem mass spectrometry.In putative normal DBS specimens from newborns (N=223) C26:0-LPC was 0.09±0.03 μmol/l whole blood, while in peroxisomal biogenesis disorder (including X-ALD) patients (N=28) C26:0-LPC was 1.13±0.67 μmol/l whole blood. Both multiple reaction monitoring and a neutral loss scan (225.1 Da) analysis of DBS were used to analyze LPC.Compared to a previous report of C26:0-LPC analysis in DBS, the method described here is simpler, faster, and more structure-specific for LPC with C26:0 acyl chains.