Health microinsurance is a financial tool that increases utilization of health care services among low-income persons. There is limited understanding of the illnesses for which insured persons are hospitalized. Analysis of health claims at VimoSEWA, an Indian microinsurance scheme, shows that a significant proportion of hospitalization among insured adult women is for common illnesses?fever, diarrhoea and malaria?that are amenable to outpatient treatment. This study aims to understand the factors that result in hospitalization for common illnesses. Methods: The article uses a mixed methods approach. Quantitative data were collected from a household survey of 816 urban low-income households in Gujarat, India. The qualitative data are based on 10 in-depth case studies of insured women hospitalized for common illnesses and interviews with five providers. Quantitative and qualitative data were supplemented with data from the insurance scheme?s administrative records. Results: Socioeconomic characteristics and morbidity patterns among insured and uninsured women were similar with fever the most commonly reported illness. While fever was the leading cause for hospitalization among insured women, no uninsured women were hospitalized for fever. Qualitative investigation indicates that 9 of 10 hospitalized women first sought outpatient treatment. Precipitating factors for hospitalization were either the persistence or worsening of symptoms. Factors that facilitated hospitalization included having insurance and the perceptions of doctors regarding the need for hospitalization. Conclusion: In the absence of quality primary care, health insurance can lead to hospitalization for non-serious illnesses. Deterrents to hospitalization point away from member moral hazard; provider moral hazard cannot be ruled out. This study underscores the need for quality primary health care and its better integration with health microinsurance schemes.