This review assesses the usefulness of parasites as bioindicators of environmental impact. Relevant studies published in the past decade were compiled; factorial meta-analysis demonstrated significant effects and interactions between parasite levels and the presence and concentration of various pollutants and/or environmental stressors. These effects and interactions were also evident in subsets of studies that used different methods such as field surveys or experimental exposure. From this meta-analysis we conclude that parasites are useful bioindicators of environmental impact. Further, by examining aspects of study design, we put forward recommendations for the design of future studies to evaluate anthropogenic impact on host–parasite interactions and increase the efficiency of environmental monitoring programs.