There is not much information about the risk factors for filariasis transmission in Southwest Sumba Regency, East Nusa Tenggara. To obtain this information, we conducted an epidemiological study of the incidence of filariasis infection in Kahale Village and Radda Malando Village, Balaghar District. The factors investigated were gender, age, occupation, occupancy density, knowledge, use of mosquito nets, nighttime habits, use of mosquito repellent, habit of hanging clothes in the room, physical condition of the house, proximity to mosquito breeding habitats and close to people with filariasis. This type of research is analytic observational where the sample was taken using case control as many as 64 people. The research instrument used a questionnaire and check list. Data analysis used the SPSS program statistical test with Backward Logistic Regression Test. The results of the bivariate test showed that the variables that had a relationship with the incidence of filariasis were the use of mosquito nets, the habit of going out at night, the habit of hanging clothes in the room with a p value <0.05. The prediction model for the incidence of filariasis with the ability to predict is 88.8% with the following equation: Y = -10,609 + 5,148 use of bed nets + 3,318 night out habits. The study showed that two variables were risk factors for filariasis, namely the habit of using a mosquito net (OR 172.18) and the habit of going out at night (OR 27.596). We conclude that the behavior of using bed nets and the habit of going out at night plays an important role in increasing filariasis infection so that it is important to change aspects of community behavior to reduce the incidence of filariasis infection.