Introduction: Internet interventions for alcohol problems are effective, but not all participants are helped. Further, the importance of adherence has often been neglected in research on internet interventions for alcohol problems. Prediction analysis can help in prospectively assessing participants' probability of success, and ideally, this information could be used to tailor internet interventions to individual needs. Methods: Data were obtained from a randomized controlled trial on internet interventions for alcohol use disorders. Twenty-nine candidate predictors were run in univariate logistic regressions with two dichotomous dependent outcomes: adherence (defined as completing at least 60% of the treatment modules) and low-risk drinking (defined as drinking within national public health guidelines) at two time points - immediately post-treatment and at the 6-month follow-up. Significant predictors were entered hierarchically into domain-specific logistic regressions. In the final models, predictors still showing significant effects were run in multiple logistic regressions. Results: One predictor significantly predicted adherence: treatment credibility (as in how logical the treatment is and how successful one perceives the treatment to be) assessed during the third week of the intervention. Four predictors significantly predicted low-risk drinking at the post-treatment follow-up: pre-treatment abstinence (i.e., not drinking during the 7 days before treatment started), being of the male gender, and two personality factors - a low degree of antagonism and a high degree of alexithymia. At the 6-month follow-up, pre-treatment abstinence was the only significant predictor. Conclusion: Adherence was not predictive of low-risk drinking. Personality variables may have predictive value and should be studied further. Those who abstain from alcohol during the week before treatment starts have a higher likelihood of achieving low-risk drinking than people who initially continue drinking.