<i>Objective:</i> To investigate the phenotype and genotype of 3 unrelated children with triple A syndrome from southern Turkey. <i>Methods:</i> The coding sequence of the <i>AAAS</i> gene was sequenced including exon-intron boundaries. Haplotype analysis using markers from AAAS region was performed in order to assess potential founder effects. <i>Results:</i> In all 3 patients, the identical nonsense mutation (R478X) in exon 16 of the <i>AAAS</i> gene was identified. The patients who may be distantly related appeared phenotypically similar with the classical triad of the triple A syndrome (adrenal insufficiency, alacrima and achalasia) with dermatological manifestations while lacking neurological features except for mild mental retardation. <i>Conclusion:</i> The R478X mutation tends to result in a rather severe phenotype although genotype-phenotype relationships cannot be drawn due to the small number of patients.