Intra vitam porous lesions of the skull (Cribra Orbitalia and Porotic Hyperostosis) are pathological conditions due to genetic or acquired chronic anaemia. They are the most reported skeletal lesions in human skeletal remains and are routinely used to assess health, hygiene and nutritional status of past populations. Despite the existence of a number of proposed classifications, there is no generally accepted classification system used by all, with clear advantages over the others. Here, we propose a new evaluation form (BoPLE-Bone Porous Lesion Evaluation) that takes in consideration all the observable features of bone porous lesions, integrating existing qualitative criteria for the evaluation of severity and healing’s conditions with a new quantitative analysis based on the count of pores per square centimetre. Porotic Hyperostosis and Cribra Orbitalia were investigated using the newly developed evaluation forms on 189 cranial bones from several distinct archaeological sites. Reliability and reproducibility of both existing qualitative scoring criteria and the new quantitative method were statistically tested. We believe that the new proposed classification system, which takes into consideration diverse parameters like surface area of lesion, location of lesion on cranial vault, and number of pits per surface area, represents a progress in the objective evaluation of porous bone lesions. Its use will allow the determination of the severity of the lesion and thus provide data to assess conditions of frailty in past populations.