We analyse the demand for and the supply of night visits in primary care. We present a model of general practitioners (GPs) choice between meeting demand by making visits themselves or passing them to commercial deputising services. We extend previous models of demand management to allow for demand discouragement as well as demand inducement. Demand and supply equations are derived and estimated using 1984/1985-1994/1995 panel data for English primary care health authorities. Demand is not affected by the likelihood that the visit is made by a GP or a deputy, suggesting that patients do not perceive these visits as being of different quality. The introduction of differential fees for GP and deputy visits in April 1990 led GPs to increase their own visits and to reduce the number made by deputies. The fee change also led to demand being managed downward where GPs used deputies and to demand inducement where they met demand themselves.