As science and technology develop, the use's areas of Fuzzy Logic Theory develop too. Measurement and evaluation in education is one of these areas. The purpose of this research is to explain the influence of fuzzy logic theory on students' achievement. An experimental method is employed in the research. The traditional achievement marks and The Fuzzy Logic Theory-based achievement marks of students are calculated and compared in the research. In the result, a significant difference between the traditional achievement marks (X-bar = 52.77; S = 17.92; N = 32) and Fuzzy Logic Theory-based achievement marks (X-bar = 64.84; S = 12.87; N = 32) are found in favour of fuzzy logic (t = -10.87; p < 0.05; r = 0.61).