This study examines the effects of general health and chronic diseases on the labour force participation of older working-age Australians. To account for potential endogeneity of health status, a simultaneous equation model is estimated and chronic diseases are used as instrumental variables. The effects of chronic diseases on labour force participation are assessed indirectly using the parameters estimated from the simultaneous equation model. The results show that both health status and chronic diseases have significant effects on labour force participation. It also appears that the effects of chronic diseases are more accurately estimated from the simultaneous equation model than from a single equation labour force participation model.