Currently, there is no FFQ designed to capture the intakes of the long-chain (LC) n-3 PUFA. The objectives of this study were to validate a new LC n-3 PUFA FFQ by comparison with 3 d weighed food records (FR) and to determine its reproducibility assessed 4 to 6 weeks apart. Healthy male and female subjects (n 53) were recruited from Wollongong and the Australian Capital Territory, Australia. The FFQ and FR were analysed for LC n-3 PUFA intakes using a nutrient analysis software package and these intakes were compared using Wilcoxon signed rank tests and Spearman correlation coefficients. Bland–Altman analysis and quintile assignment assessed the agreement between the two methods and the FFQ's ability to rank individuals according to intakes, respectively. Comparison of intakes from FFQ and FR correlated significantly for total LC n-3 PUFA, EPA, docosapentaenoic acid (DPA) and DHA, 0·75, 0·64, 0·62 and 0·72, respectively (P < 0·05); hence, there is reasonable agreement between the FFQ and the FR in assessing LC n-3 PUFA intakes. Quintile assignments correctly assigned 49 % of subjects into the same quintiles and 87 % of subjects were correctly assigned either to the same or adjacent quintiles. The FFQ was reproducible for intakes of LC n-3 PUFA, EPA, DPA and DHA with Spearman correlation coefficients of 0·88, 0·88, 0·90 and 0·87, respectively. In conclusion, the new FFQ is a valid and reproducible method that can be used to estimate the LC n-3 PUFA intake of healthy adults.