The paper presents problems related to the costs incurred for environmental protection in Polish dairy cooperatives. It was found, inter alia, that the costs of environmental protection in this industry sector are high and are rising rapidly. The costs of sewage disposal and treatment are of key importance as they represent the largest share in the total costs of environmental protection, i.e. nearly 95%. In 2018, they amounted to approximately PLN 1.5 million per cooperative, which was almost three times more than in 2004. Other environmental protection costs account for approximately 5% of total environmental protection costs. So, the key to environmental success in dairy cooperatives is rational wastewater management. Therefore, it is advisable for managers to consider building their own wastewater treatment plants with sizes and parameters appropriate to the scale of milk processing and the number of finished product ranges produced. The study also found that the costs of training employees and farmers on environmental protection are low, which may suggest the desirability of increasing them according to real needs, so as to ensure an appropriate level of understanding and persuasion of farmers -shareholders for further investments related to environmental protection. It was also found that the scale of milk processing and the number of manufactured assortments strongly affect the total costs of environmental protection of dairy cooperatives in Poland. Legal requirements regarding environmental protection are so restrictive and economically effective that their omission may lead to increasing financial, management, technological and legal difficulties. Therefore, the compliance of dairy cooperatives with legal environmental requirements is a must, which should generally be assessed positively