Stigma may influence the use of HIV pre-exposure prophylaxis (PrEP). However, there is an absence of robust measures for PrEP-related stigma. We describe an adaptation of a HIV stigma scale for use in PrEP users and experiences of PrEP users in Wales (UK) with regards to PrEP-related stigma. A mixed methods study was conducted where PrEP users completed questionnaire items about PrEP-related stigma and a subset were interviewed about their experiences of taking PrEP. We adapted items from the HIV stigma scale and assessed construct validity and internal consistency. We analysed interview data using a framework approach, with themes focussing on enacted and anticipated stigma in order to identify areas for scale refinement. Our measure had good psychometric properties but additional items may be useful (e.g. specific instances of enacted stigma, concerns around homonegativity). Further work is needed to develop this scale and validate it in a larger sample.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10461-022-03967-0.