Abstract :Clinical pharmacists (also called pharmacotherapists) are healthcare professionals that help physicians to optimize the clinical services including therapies and diagnostics and to provide the best possible health outcomes. They are also totally competent experts that can direct the process of standard medical practice individually. There are lots of clinical tasks in daily practice which could only be accomplished optimally by clinical pharmacists like stratification of poly-pharmacies, medication reconciliation, pharmacokinetic (PK)-based dosing and some physician/patient educations. Recently, categorization of medical services in numerous specialized or sub-specialized fields and continuous development of new medications make this role in clinical wards, even more critical. Increasing utilization of novel medication including expensive biotechnological products in ultimately complicated settings with huge health and financial burdens obligates the presence of considerably involved clinical pharmacists. An exquisite example of such situations is hematopoietic stem cell transplant (HSCT) settings.