Klinefelter syndrome (KS) is a common genetic condition that is currently under-diagnosed. The phenotype is broad, with physical, medical and psychosocial features ranging from mild to severe. When a child is diagnosed with KS, the parents may spend months to years searching for a diagnosis. This study used a qualitative methods approach to explore parents' experiences of having a child with KS and receiving a diagnosis. Fifteen semistructured one-to-one in-depth interviews were conducted to explore their experiences and views. The interviews were then transcribed, coded and thematically analysed. The interviews revealed that parents had diverse experiences related to: the timing of the diagnosis of their child and reasons why their child was investigated for KS; the information that was provided at the time of diagnosis; the supports that were available and the concerns that parents held for the future of their child. The conclusions from this study were that parents' experiences of having a child with KS and receiving a diagnosis were complex and multifaceted. This experience was shaped by the timing of when the diagnosis was received, who provided the diagnosis, what information was provided from health-care professionals and that which parents may have encountered on the internet. The long-term experiences for parents were also impacted by the level of support they received. These findings have implications for the process by which KS is recognised by the health-care community and supports available for families.