Aim: To explore parents' experiences at the time of diagnosis of complex congenital heart disease (CHD) for their infant, and to compare whether experiences differ when receiving an antenatal versus postnatal diagnosis. Background: The time point at which parents receive a diagnosis of CHD has changed over the years due in part to advancements in fetal ultrasound; however, CHD still remains undiscovered until after birth in some cases. The psychological impact of time of diagnosis on parents' experiences has not been well researched. Method: Descriptive and thematic analysis of primary mixed qualitative and quantitative data, collected during 2012-2013, from an online survey of parents (n=28) of infants who had undergone stage one surgery for a functionally univentricular heart. Findings: Four themes emerged: parents' understanding of the condition, parents' feelings at the time of diagnosis, sources of support and sources of additional information. Conclusion: There are implications for practice in terms of who provides the diagnosis and more importantly how well this is explained. Professionals need to assess parents' emotional status, information needs and level of understanding irrespective of time of diagnosis, so that support is individualised, sensitive and time appropriate.