The main objective of the research presented in this thesis was to gather evidence on the effectiveness of a number of procedures routinely performed in patients receiving high dose chemotherapy for hematologic malignancies. This was done both by performing systematic reviews and by performing clinical studies, and focused on different aspects of supportive care for this vulnerable patient group. The ultimate goal was on the one hand to promote medical and nursing interventions of proven evidence based benefit, and on the other hand to restructure or discourage ineffective interventions, which should both lead to improvement of the quality of care.