BACKGROUND: Clients with severe mental illness are known to have higher morbidity than the general population, but little is known about their perception of disease burden. OBJECTIVE: This study examined the disease burden in a cohort of community-dwelling persons diagnosed with severe mental illness. STUDY DESIGN: This was a descriptive study that included: interviews, measures of blood pressure, height and weight, and chart audits from 109 volunteers. RESULTS: Mean scores on the Medical Outcomes Study Short Form–12 (MOS SF-12) were compared by gender and five chronic illnesses. The participants had lower scores on the physical (PCS) and mental (MCS) health components of the MOS SF-12 than the general population. Participants with depression, hypertension, arthritis, diabetes, and chronic lung disease scored lower than the general population on the PCS and MCS. CONCLUSION: This study suggests that clients with severe mental illness and physical health problems experience a greater disease burden than do their counterparts in the general population.