A community-based cross-sectional study was conducted among brothel-based sex workers of West Bengal, eastern India, to understand sex-trafficking, violence, negotiating skills, and HIV infection in them. In total, 580 sex workers from brothels of four districts participated in the study. A pretested questionnaire was introduced to study their sociodemography, sex-trafficking, violence, and negotiating skills. Blood sample of 4-5 mL was collected from each sex worker using an unlinked anonymous method to study their HIV status. Data were edited and entered into a computer using the Epi Info software (6.04d version). Both univariate and multivariate analyses were done to find out any association between HIV and relevant risk factors. Results of the study revealed that a sizeable number of the participants were from Nepal (9%) and Bangladesh (7%). The seroprevalence of HIV was strikingly higher among Nepalese (43%) than among Bangladeshis (7%) and Indians (9%). Almost one in every four sex workers (24%) had joined the profession by being trafficked. Violence at the beginning of this profession was more among the trafficked victims, including those sold by their family members (57%) compared to those who joined the profession voluntarily (15%). The overall condom negotiation rate with most recent two clients was 38%. By multivariate analysis, HIV was significantly associated with sexual violence (odds ratio=2.3; 95% confidence interval 1.2-4.5). The study has documented that the trafficked victims faced violence, including sexual violence, to a greater magnitude, and sexual violence was associated with acquiring HIV in them. There is a need for an in-depth study to understand the problem of trafficking and its consequences.