The 6000 series aluminium alloys (Al-Mg-Si systems) are commonly used as medium-strength structural materials; in particular, the 6061 (Al-1Mg-0.6Si) alloy is widely utilized as a general-purpose structural material due to its excellent formability and corrosion-resisting capabilities. The objective of this study was to obtain a correlation between the small punch (SP) test estimated equivalent fracture strain (��qf) and fracture toughness (F1C) property for 6061 aluminium, and determine its viability as a non-destructive fracture toughness test technique for remaining life assessment of in-service components. Samples of 6061-T6 aluminium were cut from bulk plate, in both the longitudinal and transverse directions, for the as-received condition as well as subjected to three different over-ageing heat-treatment schedules. A strong linear correlation between valid F1C and SP estimated biaxial fracture strain ��qf is presented for aluminium 6061 at room temperature. �� 2007 Australian Nuclear Science and Technology organisation Journal compilation �� 2007 Blackwell Publishing Ltd.