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Introduction and aim: Crowding after orthodontic treatment occurs frequently and can be frustrating for both patient and practitioner. Crowding is also common in patients who did not receive orthodontic treatment, often as a result of normal physiological processes that involve growth and aging. Lower anterior crowding is considered as one of the most common kinds of relapse. In this retrospective study, lower anterior crowding was followed up until five years after treatment. Materials and methods: Patients treated for crowding in the lower front without mandibular extractions were selected from the archives of the Orthodontic Department of the University Hospital in Leuven. Only patients with models available from before treatment, at the end of treatment and at least at one follow-up control (around 1, 2 and/or 5 years; AB1, AB2 and AB5 respectively) were included. For each of these models, Little's irregularity index (LII), Arch length discrepancy (ALD), Intercanine (IC) and Intermolar (IM) distance, Overjet (OJ) and Overbite (OB) were determined digitally. Data were statistically analyzed using scatterplots and one-way ANOVA, as well as descriptive statistics. Results: 148 patients were finally included from the initial sample, with a median age of 14,27 years after treatment. No significant correlation between the irregularity index and time after the end of treatment was found in the present study. Based on the median values at the different time points, an increase in LII of 0,30-0,55 mm was found. A significant, however weak increase in ALD was shown in the scatterplot, but not in ANOVA. Posttreatment changes in median ALD of respectively -0,19mm in the AB1 group, +0,15mm in the AB2 group and - 0,60 mm in the AB5 group were seen during follow-up. No significant changes were found after treatment for both IC and IM. OJ and OB increased slightly after treatment, although these values were small and of no clinical significance. Conclusion: This study shows that there is no significant correlation between crowding and time after the end of orthodontic treatment. All parameters examined showed a tendency to return toward initial values, however further investigation is needed taking into account the limitations of the present study.