Aims: To assess the cognitive, and behavioural and emotional functioning of children aged 3 months to 7 years shortly before elective cardiac surgery or elective interventional catheterisation. Methods: We used the Bayley Scales of Infant Development, and the McCarthy Scales of Children's Abilities, to measure cognitive functioning. The Child Behavior Checklist was used to assess behavioural and emotional problems. Results: We found no significant differences in mean cognitive scores for children scheduled for cardiac surgery or interventional catheterisation when compared with reference groups. This was also the case for children awaiting cardiac surgery as opposed to those awaiting interventional catheterisation, and for those below as compared to those above the age of 2.5 years. Overall, our results regarding behavioural and emotional functioning were comparable to those of normative reference groups. The only difference found was that the children scheduled for cardiac surgery and aged from 2 to 3 years had significantly higher scores on the Child Behavior Checklist than did peers from normative groups. Conclusion: Cognitive, and behavioural and emotional functioning, both for young children awaiting elective cardiac surgery and interventional catheterisation, can be considered as quite favourable.