Osteopathy and chiropractic represent two challenging domains with a specific degree of multiplicity and complexity. This makes a complete appraisal difficult and impossible to appreciate in one single analysis. These disciplines exist since more than one century. An hermeneutic approach permits to understand their genesis but indicates also the nonsense of trying to transfer and apply earliest principles nowadays. It seems that most, but not all, practicing clinicians take into account recent developments in physiology, biomechanics and pathophysiology. Clinical studies and especially their meta-analyses on base of precise criteria permit to clarify the indications, therapeutic efficiency as well as socio-economic advantages. The meta-analyses point also at the poor quality of most clinical studies even if in the last years an improvement can be noted. Fundamental studies exist in both domains revealing interesting information that have permitted to reject several preconceived ideas and to clarifs others. Research topics as the morphology of the intervertebral disk before and after application of a manipulative technique are discussed. Results of experimental determination of global and segmental amplitudes in the cervical and in the lumbar spine during a manipulation in healthy subjects are reported. Finally the necessity but also the difficulties inherent to research studies in osteopathy and in chiropractic will be discussed.