Objective: Cancer can affect an individual’s level of physical function and health related quality of life (HRQoL). Those requiring hospital admission may be at risk of further decline during hospitalisation. The aim of this study was to investigate physical functioning and HRQoL of cancer patients on admission and over the course of their hospital admission. Methods: A prospective observational study was undertaken on the inpatient wards of a specialist oncology hospital. Assessment measures were taken bi-weekly until discharge from hospital or if they became too unwell to continue. Functional outcome measures included timed-up and go test (TUG), 30 second sit to stand test (30SST), 30 second arm curl test and isometric muscle strength (30ACT). HRQoL was assessed via the EORTC-C30 and SF-8 and distress was measured using the Distress Thermometer. Results: Fifty-five patients (28 males), mean age 64 years ± 10.8, with an average length of stay of 19 days participated in the study. Primary reasons for hospital admission included; symptom management (36%) or delivery of cancer treatment (35%). On hospital admission, the majority of patients scored worse than normative levels on the EORTC-C30 and SF-8. Similarly, 65%, 69% and 35% recorded below age norms for TUG, 30SST and 30ACT. Most measures showed a trend towards worsening during hospitalisation with up to 59% of patients experiencing ± 10% worsening over time. However, only role and social functioning (p < .05), as well as financial difficulty showed statistically significant worsening (p < .05) during hospitalisation. Conclusions: Participants demonstrated substantially reduced HRQoL and physical functioning at time of hospital admission which tended to worsen during hospitalisation. Despite this low level of function, very few received rehabilitation follow-up. Screening programs using HRQoL and functional assessment measures could be useful in identifying patients who are deconditioned or at risk of deconditioning and require specialised therapy to prevent declines in function and hospital re-admissions.