Health seeking behaviour depends on trust in the health services and cost of services. Determinants of health seeking behavior include socio-economic status, culture, politic and current health. During the past decades, health seeking behavior has changed from traditional to western medicine and from public to private hospitals. Estimating this change is necessary for public health planning and resource allocation. The purpose of this study was to explore the health seeking behavior and its determinants in a Jaffna community in Northern Province of Sri Lanka. The study was an analytical cross-sectional survey conducted in Sri Lanka at household level. The data were collected through face-to-face interview using a questionnaire. Estimated sample size was 724 families, which were selected by multistage stratified cluster population proportionate random sampling method.Descriptive statistics was applied to summarize the variables. Inferential statistics was used to find the relationship between treatment type, institution type and socio demographic characters. Multivariate logistic regression was applied for determinants of health seeking behavior. Among the sample, 467 families or 863 participants were ill due to 5 selected diseases during the previous month, resulting in the incidence rates of illness 240 cases per 1000-person-month. The highest and lowest incidence was observed in cold plus flu (119 per 1000-person-month) and urinary tract problem (1 per 1000-person-month), respectively. Majority of the patients received institutional treatment (55%) while self-medication was accounted for 45%. Western medicine, traditional medicine, and the mix of both treatments were used by 65%, 11% and 24% of the patients respectively. Type of illness is a significant factor predicting health seeking behavior (p<0.001). Western style treatment at government hospital was the most common health seeking behavior among the patients in this study while important determinant was type of illness.