A review of the biomedical literature suggests that lymphocyte and neutrophil counts are probably the only blood cell count parameters whose independent pre-therapeutic prognostic values are significantly documented in lung cancer (and only in non small cell lung cancer). The independent pre-therapeutic prognostic value of these two parameters remains quite controversial however, and further studies should be conducted, and in particular, comparisons between neutrophils, lymphocytes, and serum cyfra 21-1. For the therapeutic follow-up, further prognostic evaluation studies are also necessary for blood cell count parameters as well as for serum cyfra 21-1. Clinical biologists still have to convince clinicians and/or journal editors that it is not scientifically acceptable for publications to omit detailing the analytical and pre-analytical methodologies used for blood cell count measurements.