Macro　polyolefin　fibres　can　effectively　improve　flexural　toughness　and　post-cracking　performance　of　concrete,　they　are　hence　becoming　popular　in　various　constructions.　This　research　focused　on　quantifying　reinforcing　effects　of　macro　polyolefin　fibres　in　concrete　using　round　determinate　panel　test.　Effects　of　fibre　length,　fibre　dosage　and　concrete　strength　on　the　toughness　of　fibre　reinforced　concrete　were　investigated.　A　new　characterisation　method　using　toughness　index　was　preliminarily　attempted　to　introduce.　It　reflects　the　degree　to　which　the　fibre　changes　the　toughness　of　plain　concrete.　It　also　＂normalises＂　the　toughness　into　approximately　the　same　magnitude　with　other　flexural　tests,　making　it　possible　to　compare　with　different　flexural　tests.　(C)　2016　Elsevier　Ltd.　All　rights　reserved.