Drinking coffee has been inseparable from the daily habit of Indonesian society. However, there have been debates between the benefits and disadvantages of consuming coffee due to the existence of caffeine as a prominent substance in coffee.1,2 Caffeine in coffee includes psychostimulant substance that keeps people awake, decreases fatigue, and raises energy. Therefore, consuming cofee can also keep body fitness to excellently perform daily activities.2-3 This research aimed to find out the effect of consuming instant coffee on the fitness level of medical students in Islamic University of Indonesia (IUI) using Mc Ardle step test. This researsch is an experimental study using post-test control group design. The research protocol had been approved by the Ethical Committee of Faculty of Medicine, IUI no. 24/Ka.Kom.Et/70/KE/II/2016. The subjects were 51 female medical students in IUI, who were suitable with the inclusion and exclusion criteria and were randomly classified into three groups. Group 1 was the control group, consisting of students who consumed 200 cc solution containing mocca essence and 1 sachet low calorie sugar. Group 2 consisted of students who consumed 200 cc solution containing full-dose instant coffee (2 spoonful or 7.45 grams coffee powder) with 158 mg caffeine and 1 sachet of low calorie sugar. Group 3 involved students consuming 200 cc solution containing half-dose instant coffee with 79 mg caffeine and 1 sachet of low calorie sugar. The fitness level of the subjects was measured using Mc Ardle step test 60 minutes after treatment.4-5 Pulse rate was measured twice, i.e. before treatment and after fitness test. The results were mean+SEM analyzed using one way ANOVA test. The result was defined as statistically signifcant when p<0.05. The analysis of average pulse rate before treatment showed non significant difference among the groups (p=0.41). The result means that the pre-condition of one group was equal with others. The analysis of pulse rate after Mc-Ardle step test showed that there was significant difference between the groups (p=0.00). The measurement of group 1 (176.94+5.99) showed the highest pulse rate, continued by group 3 (159.06+7.13), and group 2 (139.29+3.78). The result implied that post-test-physiological-adaptation of the group consuming coffee was better than the control group. Meanwhile, the analysis of average fitness index after treatment showed that there was significant difference among the groups (p=0.00). The best index was gained by group 2 (40.08+0.70), followed by group 3 (36.43+1.32), and group 1 (33+1.10). It means that the students consuming coffee had better fitness level than those of the control group. In conclusion, instant coffee consumption has significant effect in raising the index of fitness level based on Mc-Ardle step test.