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Background: Williams–Beuren syndrome (WBS; OMIM #194,050) is a rare multisystem disorder of a variable phenotypic spectrum caused by a heterozygous microdeletion in the WBS chromosome region (WBSCR) in 7q11.23. Methods: We screened 38 Chinese Han patients with suspected WBS using chromosomal microarray analysis (CMA). Results: Pathogenic CNVs were identified in 34 of the patients, including 29 cases with a typical 7q11.23 microdeletion, three cases with atypical copy number variations (CNVs) within the WBS chromosome region and two cases with CNVs associated with other known syndromes. All 29 WBS patients with a typical microdeletion exhibited distinctive facial dysmorphisms and developmental delay. We observed that the incidence of pulmonary abnormalities was slightly higher than that of aortic abnormalities. We also found long philtrum and prominent lips with a thick lip that may warrant suspicion of WBS in the Chinese Han patients. Conclusion: CMA facilitates diagnosis in individuals with classic/nonclassic features of WBS and demonstrated that when Chinese Han patients present with a less classical phenotype, such as pulmonary abnormalities, this may raise suspicion for a WBS diagnosis and suggest a referral for a genetics evaluation for a differential diagnosis. Our study demonstrates that although the clinical features of WBS display a highly variable phenotypical spectrum, CMA facilitates diagnosis in individuals with classical and nonclassical features of WBS. In Chinese patients, a less classical phenotype in other races and ethnicities, such as PAS, long philtrum, and global developmental delay, should raise suspicion for WBS and suggest referral for a genetics evaluation and a differential diagnosis. [ABSTRACT FROM AUTHOR]