Chikungunya fever is a vector-borne disease with high morbidity rates it caused socioeconomic impact. On 17 January2014, an outbreak of Chikungunya fever was reported in Batang Toru Sub-district, South Tapanuli District, North Sumatera.The total number of cases were 74 with no fatalities. An analytical study with case control design was undertaken todetermine the risk factors of the outbreak. The cases were population with major clinical symptoms of Chikungunya, such asfever, arthralgia, myalgia, rash and headache. Controls were neighbours of the cases who did'nt have clinical symptoms ofchikungunya. The study used bivariate analyses with chi-square and logistic regression (95% confidence level). Somepatient's blood were tested with rapid diagnostic test (RDT) of IgM Chikungunya. The bivariate analysis showed thatvariable associated with the incidence of chikungunya were sleeping without bednets in the morning anf afternoon (p- value:0,000; OR= 4.825, CI= 2.379-9.782) and the mosquitoes larvaes in the water reservoirs around the house (p-value: 0.013;OR=3.837; CI=1.322-11.131). The result of RDT confirmed that two of seven cases were positive for IgM Chikungunya.Outbreak of chikungunya fever was confirmed. Chikungunya transmission occured continuosly and the source oftransmission was more than one person.