The objective of this paper was to determine the administrative efficiency of environmental protection funds in Poland in the years 2006-2019. The basic research method applied in the empirical part was an analysis of data contained in the documentation of environmental protection funds. This method allows the acquisition of information on the functioning of various organizations. The subject matter of the research was the activity of 16 provincial environmental protection and water management funds as well as the National Fund for Environmental Protection and Water Management. Based on a series of 238 observations, the authors analyzed the activities of the fund system in the years 2006-2019. Having conducted a literature review, they decided that a quantifiable and applicable measure to assess the performance of the funds was their administrative efficiency expressed as percentages of resources allocated to the factual support of proposed projects and the functioning of the institutions themselves, respectively. The performed analyses covered the economies of scale and size of granted financial support disaggregated into non-reimbursable aid and reimbursable aid, as well as time series. The research showed a statistically significant relationship between the volume of provided aid and the level of costs (at the significance level of 0.05). The examination of changes in the cost-to-aid ratio in the years 2006-2019 does not provide optimistic conclusions in terms of optimisation of operating costs incurred by individual funds. Funds with relatively low operating costs recorded lower cost increases (in percentage points) than those with high operating costs. The research indicates that there are no mechanisms forcing or motivating the funds to improve their operational efficiency. The operationalization of the relationship between the type of provided aid (reimbursable vs. non-reimbursable) and the level of costs did not show any connection (the function fit measured by the coefficient of determination R2 did not exceed 0.01).