Patients with schizophrenia have a lifespan that is more than 20 years less than that of the general population. It has been suggested that treatment with antipsychotics is a reason for their reduced lifespan, but patients with schizophrenia are also known to have a more sedentary and unhealthy lifestyle, including heavy smoking, inactivity and obesity. Some antipsychotic medications increase the risk of diabetes and dyslipidemia, but, on the other hand, suboptimal treatment increases the risk not only of suicide but also violent behaviour. Furthermore, it is known that patients with schizophrenia are less likely to seek medical help for their somatic diseases. This chapter discusses medical illnesses associated with schizophrenia and its treatment with focus on monitoring and intervention in order to reduce mortality.