Malaria is an endemic disease that has received the attention of the United Nations to be combated. There are currently 104 malaria-endemic countries and 3.3 billion people at risk of infection. Herbal medicines are traditionally consumed in many countries to overcome the disease, among them is bitter gourd (Momordica charantia) that enhances the immune system. This research aims to study the effect of bitter gourd leaf extract as an immunomodulator against the growth of Plasmodium berghei in Balb/C mice, observing the pre-incubation time, parasite growth, phagocytic activity, and antibody titers. In this research, the gourd leaf extract was given to the mice every two days during a seven-day period before the infection. The concentration of the extract was 125 mg/ml and 62.5 mg/ml. The number of injected parasites were 20 million and 2 million. Parasitemia level was observed everyday after the infection, whilst phagocytic activity and antibody titers were observed before the treatment, before the infection, and every six days after the infection. The research showed that bitter gourd leaf extract resulted in a longer preincubation time (5 days) and a lower level of parasitemia at 125 mg/ml. Interestingly, an increase in phagocytic activity (74,58%) and a higher antibody titers (7,32 at Log2) were found at 62,5 mg/ml.