The dynamics of cheese purchases is analyzed by estimating a series of econometric models of duration based on a 170 week household panel. Besides purchase quantity and price data, information with respect to coupon use and household demographic characteristics are used in a variety of models which build upon each other in terms of assumed distribution of interpurchase time, effect of previous purchases, role of demographic characteristics and effect of unobserved interpurchase time heterogeneity. Likelihood ratio tests clearly reject the null hypothesis that coupon use has no impact on cheese purchase timing.