OBJECTIVES Interest in delivering Patient Reported Outcome Measures (PROMs) using mobile devices (e-PROMs) has increased in recent years.  However there is debate about the level of equivalence between the traditional pencil and paper and electronic modes of administration.  The aim of this study is to compare the equivalence of delivering a widely used generic PROM (EQ-5D-5L) pencil and paper and mobile phone administration modes. METHODS A mobile version of the EQ-5D-5L was developed with guidance from the EuroQol Group.  Two hundred respondents from a research cohort of people in South Yorkshire were identified, and randomly allocated to one of the administration modes based on stratifications for age and gender (and across a range of self-reported health issues). The EQ-5D-5L was completed either using a mobile device or the standard paper version which were sent out to the respondent.  Follow up usability questions were also included.  EQ-5D equivalence was compared at the dimension and utility and VAS score level using ANOVA. RESULTS Response rates were comparable across the arms, with the majority of respondents owning a smartphone.  The mean EQ-5D-5L utility and VAS scores and the frequency of respondents endorsing the individual EQ-5D-5L categories across each of the dimensions does not differ across the administration modes. The majority of the mobile phone completion sample agreed that the mobile version of EQ-5D-5L was easy to complete, and that the phone was easy to use, and that they would complete e-PROMs again. CONCLUSIONS Completing e-PROMs using mobile phones produces equivalent results and response rates to pencil and paper methods, and respondents are positive towards completing questionnaires using these methods. This provides evidence that e-PROMs are valid for use to collect data in a range of settings including clinical trials, routine care, and as, for example, health diaries.