The work presented in this article focuses on the environmental impact of hydraulic fluids used in forestry. Migration and biodegradability of three biolubricants and a mineral lubricant were monitored in two forest soils and in a liquid medium. These studies proved that biolubricants were easily degradable products and showed ultimate biodegradability rates significantly higher than those of the fluid of mineral origin, specially in a soil environment. This superiority was even greater when fluid behaviour was observed after 1000h of use. Ecotoxicity test enabled the classification and comparison of biolubricants and showed that toxicity levels of the biolubricants were never high however, even after use, as compared to petroleum-based fluid.