5Alpha-reductase 2 deficiency is an autosomal recessive disorder characterised by lack of masculinisation in XY individuals due to failure to convert testosterone to dihydrotestosterone, the bioactive androgen. Traditionally, the testosterone-to-dihydrotestosterone ratio is used to diagnose this condition but interpreting these results is not always straightforward, thus they may be inconclusive. On the contrary, urinary steroid profiling unambiguously demonstrates a significantly reduced excretion of 5alpha-reduced steroid metabolites compared to their 5beta counterparts. This analytical technique can also simultaneously confirm or rule out other causes of ambiguous genitalia due to steroidogenic defects. Making a DNA-based diagnosis by studying the SRD5A2 gene has become increasingly popular. Here, we report six Chinese patients from different families who were all diagnosed with 5alpha-reductase 2 deficiency based on urinary steroid profile findings and mutational analysis of the SRD5A2 gene. R227Q was the most commonly identified mutation in these patients. Management of sexual development disorders is also discussed.