Introduction The general-purpose rating scales used by clinical pharmacists to rate their activities have not been extensively studied in specialist care units. This study aims to describe drug-related problems (DRPs) and pharmacist interventions (PIs) in a French hematopoietic cell therapy (HCT) unit and to evaluate the PIs’ likely clinical, economic, and organizational impacts. Methods We retrospectively assessed all DRPs reported and all PIs issued between December 2018 and December 2021. The Act-IP scale was used to rate DRPs and PIs, and the ClEO scale was used to rate each PI's clinical, economic and organizational impacts. Fisher's exact test was used to assess the relationships between PIs and DRPs and between the three dimensions of the ClEO scale. Results The DRPs were most frequently related to drug-drug interactions (16.5%), physicochemical incompatibilities (15.5%), and drug monitoring problems (14.9%). 62.8% of the PIs had at least a moderate clinical impact. PIs that recommended drug monitoring were most frequent (26.8%), and most of these (75%) were likely to have prevented incidents that would have required patient monitoring or treatment. Conclusions The results of this study showed that after a slight adaptation, the Act-IP scale can be used to map clinical pharmacy activity in an HCT unit. More than 60% of the DRPs/PIs were likely to have had a positive impact on the patient's clinical outcome. All the PIs were rated with a positive organizational impact and PIs likely to lead to cost savings were balanced by those likely to increase costs.