Biodiversity is recognizably affected by land conversion for agriculture. However, the assessment of impacts on wildlife often lacks information on populations structure and individuals' condition, allowing only a limited view of the problem. Individual body condition/health can influence animal's reproductive success or survival. Eucalyptus globulus plantations are important forestry systems in Iberia, being the widest forested-land use in Portugal, which hosts the broadest European E. globulus coverage. We tested Eucalyptus plantations' effects on small mammals' body condition (using the Scaled Mass Index-SMI as surrogate) and ectoparasite abundance (number of mites, ticks and fleas per host). We applied a Generalized Linear Mixed Model (GLMM) approach for testing the influence of gender, habitat, species, season and understory cover on SMI and ectoparasites abundance. We captured 681 individuals, hosting overall 521 fleas (n = 305), mites (n = 159) and ticks (n = 57). Animal's body condition was not affected by plantations, but was lower for males and higher in spring. However, animals captured in Eucalyptus plantations and spring had higher parasite abundance (namely ticks and fleas), as well as males. Mites results were inconclusive. Body condition patterns seem to be determined by males demanding spatial/reproductive behavior (i.e., wider home-ranges and search for females), while plantations promote ectoparasites abundance (e.g., induced by habitat disturbance and dilution effect). Results highlight that plantations may have negative effects on wildlife, but the evaluation of anthropic landscapes impact upon wildlife should encompass several bio-ecological indicators, since the use of a restricted set (e.g., body condition) may induce a biased view.