Mycelium composites have been popular recently worldwide in terms of research interest and commercialization. Mycelium composites are biodegradable, produced renewable materials, environmentally friendly and show low density, good insulation properties, both related to acoustic and thermal aspects. However, mechanical properties of mycelium composites are obviously lower than alternative materials such as expanded polystyrene. In this study, hardwood and softwood fibers were inoculated with a white rot fungus and incubated in a climate chamber at 25 °C and 65% relative humidity for 15 and 30 days. Mycelium based medium density fiberboards were produced either without using any adhesive or with using 6% urea formaldehyde adhesive. The MOE, MOR, IB, thickness swelling and water absorption percentage of the mycelium based MDF were determined. The results showed that the MOE, MOR and IB values of the mycelium based MDF were low and did not meet the minimum required strength values given in the standards. However, these boards may still be used as insulation materials.