Purpose: This study aimed to adapt the Registered Nurse Forecast (RN4CAST) nurse survey making it appropriate to assess the working environments of ambulatory chemotherapy nurses, specifically focusing on care left undone. Method: A two-phase approach was used. Firstly, cognitive interviews were conducted to adapt role specific sections of the RN4CAST nurses survey. The interviews were analysed to assess comprehension, retrieval, judgement and response processes to create the RN4CAST-chemotherapy assessment tool (CAT) survey. Secondly, a single centre feasibility study was undertaken to assess acceptability of the RN4CAST-CAT survey in an ambulatory chemotherapy setting. Results of the feasibility study were analysed using descriptive statistics and compared with routinely collected patient experience data. Results: The cognitive interviews (n=6) resulted in important amendments to the RN4CAST-CAT. Response rate to the feasibility study was acceptable at 57% (n=12) and item completion rate was good (on average only 1 response missing per item). On average nurses looked after nine patients per shift, administered seven chemotherapy treatments and worked an hour and 10 min over their contracted time. Main areas of care left undone were related to verbal communication with patients and assessing patient comorbidities and toxicities. Conclusions: We were able to adapt the RN4CAST to make it suitable for use in the ambulatory chemotherapy setting. Our study offers preliminary evidence that the RN4CAST-CAT and methodology are feasible and acceptable within the ambulatory chemotherapy setting. Larger scale testing is now required and if validated the RN4CAST-CAT has the potential to provide useful insights into the impact of nursing workload on staff experience, patient care and outcomes on ambulatory chemotherapy settings.