This study assesses the willingness to pay (WTP) for social health insurance among informal sector workers in Wuhan, China, using the contingent valuation method. The study found that on average, informal sector workers were willing to pay substantial amounts (30 RMB) and proportions of their incomes (4.6%) for the Basic Health Insurance (BHI). The WTP increased significantly when any of the copayments of the BHI were removed. The results suggest that Chinese municipal governments should allow informal sector workers to participate in the BHI, as the average WTP is significantly higher than the estimated average cost of BHI. The study also found that informal sector workers valued the BHI primarily for its protection against rare but large financial losses associated with catastrophic care, rather than for covering frequent but small financial losses from common illnesses. Government subsidies and changes in insurance attributes, such as including catastrophic care and portability, are expected to increase BHI coverage.This study assesses the willingness to pay (WTP) for social health insurance among informal sector workers in Wuhan, China, using the contingent valuation method. The study found that on average, informal sector workers were willing to pay substantial amounts (30 RMB) and proportions of their incomes (4.6%) for the Basic Health Insurance (BHI). The WTP increased significantly when any of the copayments of the BHI were removed. The results suggest that Chinese municipal governments should allow informal sector workers to participate in the BHI, as the average WTP is significantly higher than the estimated average cost of BHI. The study also found that informal sector workers valued the BHI primarily for its protection against rare but large financial losses associated with catastrophic care, rather than for covering frequent but small financial losses from common illnesses. Government subsidies and changes in insurance attributes, such as including catastrophic care and portability, are expected to increase BHI coverage.