The study examined the effectiveness of routine intervention in alcohol abuse by a general practitioner, with help of a laboratory test. Patients diagnosed as abusers because of high erythrocyte mean cell volume value (MCV) and having no other cause for it were randomly allocated to two groups: 1) an intervention group, comprising 92 patients (69 men and 23 women), who were invited for follow-up at three-monthly intervals for a year; 2) a control (mini-intervention) group, 86 patients (71 men and 15 women), who were followed-up only after 12 months. Follow-up attendance was poor, particularly in the intervention group. In general, MCV-values were unchanged in the groups at the end of the study, though there was a clear trend for the female controls to have lower values (101.9 fl at the start, 98.5 fl at the end, p = 0.06). Altogether 11% (4/38) of the women and 7% (10/140) of the men had clearly reduced their alcohol consumption after one year, and this was also seen in their MCV-values. Mini-intervention, especially in women with an abnormal laboratory value, seems to be, with the help of MCV, at least as effective a way of counselling nonalcoholic abusers as a more systematic intervention.