In epidemiology, the morbidity rate is a ratio that measures the incidence and prevalence of a specific disease. Within the framework of a given time period (typically, but not necessarily, one year) it gives the number of people who are afflicted with that disease per unit of population. It is usually expressed as a number of people afflicted per 1,000, 10,000, or 100,000 people.

Compare mortality rate, which compares the number of people who die from a disease to the number who have it; or alternatively (and probably more accurately), which compares the number of people who die from a disease to the total population.