Intuitive is a process of thinking based on intuition that is a purification of conclusions that are strongly reasoned through feeling and indispensable in learning mathematics. The research objectives were: describe the ability of mathematical intuition thinking (Kb-iM) and the effectiveness of the application of realistic mathematical approaches from students of Mathematics Education Study Program FMIPA Medan State University. The sample of the study was 36 students in the 2015 class who were / had attended the Kapita Selekta Mathematics School course. The research instrument was in the form of 8 items of objective test of mathematical intuitive thinking ability. This test was developed based on the formulation of indicators that are built from supporting theories. The results of data analysis show that: (1) for the pre-test Kb-iM the range = 0.88; smallest score 2.38; biggest score of 3.25; average = 2.86 and standard deviation = 0.24. The same thing with the Kb-iM post-test obtained a range of values = 1.30; smallest score 2.60; biggest score 3.9; average = 3.24 and standard deviation = 0.31. Average values mean that the level of initial achievement of students’ mathematical intuitive thinking skills was only 71.5% and after realistic mathematics learning it had reached 81.0% or an increase of 10%. This fact gave the meaning that realistic mathematical learning approaches play a positive role to improve students’ mathematical intuitive thinking skills. At the end of the study it turned out that the level of mathematical intuitive thinking ability of students was at least at the moderate level.