OBJECTIVES: :  To assess content equivalence and usability between paper and electronic versions of the Psoriasis Symptom and Sign Diary (PSSD) on a handheld (24-hour recall) and tablet (7-day recall) among subjects with plaque psoriasis.   METHODS: A cross-sectional, qualitative study was conducted involving one-on-one cognitive and usability interviews in US adults with physician-confirmed plaque psoriasis. Each participant completed the 24-hour version on paper and handheld and the 7-day version on paper and tablet, before being interviewed.  Participants were randomized to order of recall period and mode administration. Interviews were conducted in two rounds with revisions made to both devices between rounds.   RESULTS: The mean age of sample (N=14) was 51 (range: 32 to 73 years); 57% were female. The majority (n=12, 86%) reported positive overall impressions of the handheld and tablet, finding them easy to use and more convenient than paper. Participants also found the PSSD content similar between versions.   In Round 1, all participants (n=7) suggested increasing the size of the NRS scale, questions or instructions on the handheld; 4 participants selected a different response than intended due to small scale size.  For the tablet, suggestions included increasing the font size and highlighting selected responses. As a result of Round 1, the font size of the PSSD was increased on the handheld, the tablet was updated to highlight the response selected in a different color, and additional training was incorporated. In Round 2, participants reported improved usability as a result of the updates; three participants suggested increasing the font size on both devices, but only 1 participant reported difficulty selecting a response on the handheld. CONCLUSIONS: This study confirmed content equivalence between paper and electronic PSSD versions and demonstrated that both handheld and tablet are suitable for use in patients with plaque psoriasis with adequate front size on the devices.