The impact of various milk pricing systems on the economic weights and the resulting selection responses for milk yield and fat and protein contents in Holstein and Czech Fleckvieh were investigated. The calculations were done for the situations with andwithout quotas. There was a substantial influence of the milk pricing system on the selection response. The use of index weights based on a ?wrong? pricing system reduced the total economic selection response by up to 51% of the selection response expected for an index based on the ?correct? pricing system. Financial losses in the selection response were greater with quotas than without quotas. Higher losses were also calculated for Holstein compared with Czech Fleckvieh. Incorrect assumptions on the output limitation led only to minor reductions in the total selection response (mostly less than 2%) if the other parameters were correct.