Aim: Firstly, to quantify active healthcare professional (HCP) time and costs associated with subcutaneous (SC) administration of trastuzumab (Herceptin^?) compared with the standard intravenous infusion (IV) in the treatment of patients with HER2-positive early breast cancer within the adjuvant PrefHer trial setting; secondly, to measure patient time in the care unit and patient infusion chair time for both routes of administration. Methods: A UK multi-centre prospective, observational Time and Motion study was conducted alongside the PrefHer trial (ClinicalTrials.gov id: NCT01401166). Trained observers measured the duration of each SC and IV related task that HCPs undertook and recorded patient time in the chemotherapy unit and infusion chair. The type and quantity of medical consumables used with each route of administration were also collected. Twenty-four patient episodes were recorded (12 SC, 12 IV). Mean total administration time was calculated as the mean sum of task times, both for IV and SC formulations. The mean cost of each route of administration was calculated as the mean cost of HCP time plus the mean cost of consumables used. HCP time was costed using Personal Social Services Research Unit. Consumables were costed using hospital pharmacy data and online sources. Results: Mean active HCP time for IV administration was 92.6 minutes compared with 24.6 minutes for SC administration. The mean cost for IV preparation and administration was ￡144.96 (￡132.05 of HCP time and ￡12.92 of consumables) versus ￡33.15 (￡31.99 of HCP time and ￡1.17 of consumables) for SC administration. Mean time spent in the care unit and in the infusion chair was 94.5 minutes and 75 minutes respectively for IV, and 30.3 minutes and 19.8 minutes for SC. SC administration of trastuzumab could translate to a time saving of 68 minutes (versus IV) with a total cost saving of ￡111.81 per