Abstract One of the fastest growing groups of gamblers in many parts of the world is older adults. We take a mathematical modeling approach to the gambling epidemiology of older adults aged 65–80. An epidemiological model with a system of four nonlinear differential equations is created. The model seeks to examine dynamics of the system through stability analysis and a basic reproductive number. The model indicates that problem gambling among older adults is present in an endemic state; the prevalence rate of serious gambling problems has been steady at about 6.5% after adjustment for exposure to the enlargement of gambling opportunities; and primary prevention is most effective. We discuss strategies for primary prevention of gambling problems among older adults. All parameters are approximated, and numerical simulations are also explored. Although research has been active on gambling, this is the first mathematical modeling approach to study the dynamics of gambling.