Broadleaf afforestation increasingly requires selecting planting material that combines valuable wood properties with resilience to climate stress. High heartwood content is a desirable trait in pedunculate oak (Quercus robur), but it is unclear whether selecting for it could compromise resistance and resilience to drought performance. We addressed this question in a progeny trial started in 2002 in southern Denmark where trees were ranked by heartwood production and the 2018 drought was used as a natural stress event. Trees with contrasting heartwood content were assessed using multiple indicators of drought response, including annual ring width, vessel anatomy, wood density, and dual stable isotopes (δ¹³C and δ¹⁸O) measured in earlywood and latewood over five years. The 2018 summer drought (SPEI3 approximately -1.5) was clearly reflected in isotopic signals, indicating that trees perceived the water deficit. However, radial growth did not decline, and ring widths remained above average in 2018. Climate-growth relationships suggested that growth at this site is more strongly limited by cool springs or wet summers than by moderately dry early-summer conditions. Across all metrics, trees with lower and higher heartwood content showed broadly similar physiological and wood-structural responses. Within the environmental conditions and drought intensity observed here, these findings do not provide evidence for a strong trade-off between heartwood content and drought response. They therefore support, with appropriate caution, the continued consideration of heartwood content as a selection trait in breeding and afforestation programs in comparable environments.