The present study assessed mental well-being daily in 28 alcohol-dependent patients who underwent 28 days of Minnesota inpatient treatment. The Swedish Mood Adjective Check List (sMACL) with six bipolar dimensions was used for daily self-reports. At start of treatment, patients had lower levels in four dimensions of mental well-being compared to those of a norm group. Moreover, patients showed significant improvements in all levels of mental well-being during treatment, and at the end of treatment patients had values within the normal range, except for one dimension (activation/deactivation), in which the levels were significantly higher. The findings may suggest a beneficial effect of this type of treatment on mental well-being, although findings may also reflect a mere effect of adjustment to treatment or the social situation.