Health insurance schemes established to improve health financing in Tanzania faces many challenges including low acceptability. Therefore, the study to assess the determinants of health insurance participation among informal sector workers in rural Tanzania was undertaken. The general objective of the study was to assess issues that influence the readiness of informal sector workers to enroll in the health insurance scheme necessary for designing a pro equity health financing system. Specific objectives were to identify the reasons for participation in particular health insurance scheme; to identify the overall attitudes of the informal sector workers towards health insurance schemes and to estimate the informal sector workers enrolment into health insurance schemes. A sample of 250 respondents participated in this study. The binary logistic regression technique was used to examine the likelihood of an informal sector worker to be willing to enroll into health insurance scheme. The study showed that the acceptability of the health insurance scheme among the informal sector workers is enhanced by affordability, accessibility and quality of health services and is worsened by misconceptions, mistrust and lack of knowledge about such schemes. The overall attitude was that the health insurance should be universal, voluntary and financed by using tax shillings. Debt (p < 0.01), debt to income ratio (p < 0.05) and experience in the current occupation (p < 0.05) were strong predictors of willingness to join health insurance. Sex, income and number of dependants were not good predictors of willingness to join health insurance (p > 0.1). The policy implication of these results include the need of increasing flexibility of the scheme through innovative approaches of collecting premiums, improving affordability, establishing health financing tax and accreditation system for health facilities. These measures will enhance acceptability and deeper penetration of health insurance schemes in rural areas.Belgian Technical Cooperation (BTC)