PurposeThe present randomised controlled trial aimed to assess the effects of 8-week supplementation of n-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA) on the n-3 index and performance of professional male football players.Design/methodology/approachA total of 27 professional male football players were randomly assigned into 2 groups: placebo (n = 14) and n-3 LCPUFA (n = 13). n-3 LCPUFA supplements containing 1.5 g eicosapentaenoic acid (EPA) and 600 mg docosahexaenoic acid (DHA) were administered as 6 capsules (four in the morning and two in the evening, 30 min after a meal). Anthropometry, body composition, dried-blood spot n-3 LCPUFA levels, exercise performance and dietary intake of football players were measured at week 0, week 4 and week 8.Findingsn-3 LCPUFA supplementation improved blood levels of EPA and DHA levels, omega-3 index vs placebo (p time*group = 0.010, 0.041 and 0.018, respectively). n-3 LCPUFA supplemented group had significantly higher aerobic capacity than placebo participants, at week 8 (p group = 0.021).Originality/valueThis study shows the effect of n-3 LCPUFA supplementation in Malaysian professional male football players involved in team sports having low dietary intakes of n-3 LCPUFA.