Cigarette smoke has shown various kinds of free radical content. The increasing number of free radicals from exposure to cigarette smoke that enters the respiratory tract may result in lung tissue damage. The reason is because excessive free radicals can trigger oxidative stress due to an imbalance in the number of antioxidants in the body and trigger an inflammatory response. Alveolar macrophages are one of the defence systems in lung tissue which will increase when the number of free radicals is increasing. Giving antioxidants from outside the body can help reduce the impact of free radicals. This study aims to determine the effect of broccoli extract on the reduction of alveolar macrophages. Study is experimental using Randomized Controlled Trial design. Research process was carried out for 21 days by dividing the experimental animals into 6 groups. Each group was given a treatment cigarette smoke 2 times per day for 2 minutes. The extract of broccoli in different doses (0.5ml;0.75ml;1 ml;1.25 ml). The assessment of the number of alveolar macrophages with Hematoxylin Eosin (HE) staining, the measurements were carried out by calculating the average of 10 visual fields in each preparation. The results showed that the administration of broccoli extract resulted in a decrease in the number of alveolar macrophages (ANOVA, p=0.000). In addition, the increased administration of broccoli extract would further reduce the number of alveolar macrophages (P<0.05). It can be concluded that the intake of broccoli extract can reduce the number of alveolar macrophages due to exposure to cigarette smoke.