BACKGROUND: The wide accessibility of computer-based technologies like the Internet and Interactive Voice Response (IVR) systems raises the question of whether population survey data could be collected more easily and cheaply compared to using paper questionnaires. In the area of possibly stigmatized behaviors such as problematic alcohol and drug use, the question extends to whether the prevalence of such behaviors in the general population could be surveyed without compromising the quality of the data. AIMS: This study compares Internet and IVR versions of the AUDIT and DUDIT with respect to: (1) response rate, (2) problematic alcohol and drug use and (3) reliability. METHOD: 5000 individuals, randomly selected from the Swedish general population, were contacted via postal mail and invited to complete the AUDIT and DUDIT questionnaires via Internet or IVR. In total, 1861 (37.8%) participated in the study, 1089 via Internet and 772 via IVR. RESULTS: The Internet administration mode yielded a higher response rate (38.1%) compared to the IVR mode (33.9%). When respondents were given a choice between Internet and IVR, a higher response rate resulted (43.2-46.6%). Problematic alcohol and drug use occurred among 21.1% and 2.8% of the sample, respectively, with no significant differences by administration mode. Both the AUDIT and DUDIT exhibited satisfactory reliability across administration modes, Cronbach's α 0.76/0.86. CONCLUSIONS: Data quality does not deteriorate with computerized administration methods for the AUDIT and DUDIT in population studies but paper questionnaires should also be made available to respondents in order to maximize response rates.