The aim of this study was to describe the feasibility, advantages and limitations of the combined use of Internet and SMS technology to assess alcohol use, and to test whether an SMS sent in the evening (i.e. prior to a possible drinking event) changed the respondents' assessment, made on the following day, of the number of drinks consumed. Participants: Seventy young adults (mean age 22.7) were recruited through face-to-face contacts, e-mails and Internet advertisements. Design and setting: Participants completed a baseline assessment via Internet and were randomly assigned to two conditions (with and without evening SMS). Over four weekends, both Friday and Saturday night, drinking was assessed via SMS questions sent the next day to the participants' cell phones. Results: A high retention rate (75% in total) was obtained across all three recruitment conditions. The number of drinks indicated in the SMS survey was strongly correlated with the usual quantity assessed via Internet and did not differ depending on whether an additional SMS question was sent in the evening or not. Conclusion: The new method shares some of the advantages of conventional diaries but overcomes most of the limitations: it is easy to use, cost-effective and suitable for large-scale surveys. Application restrictions and further developments are discussed.