As clinical studies about subtypes of the cannabis withdrawal syndrome (CWS) are scant, we performed a re-analysis of longitudinal data with German adult cannabis-users seeking inpatient cannabis detoxification-treatment. Sixty-seven cannabis-dependents without active comorbidity were included for growth-mixture-analysis (GMM) of their CWS-severity-trajectories during a scheduled 24-day detox-treatment. As of treatment-day 12, thirty-six (53.7%) of 67 patients were discharged after successful detoxification. This led to artificial imputations for I-GMM. Therefore, we preferred the results of the GMM including raw data-only (R-GMM). By both, I-GMM and R-GMM, we found two classes of CWS severity time-courses. Class one (n = 44, R-GMM) showed a continuously decreasing CWS-severity; class two (n = 23, R-GMM) exhibited a sharp peak (generally between days 2-6 post-cessation). A short inpatient treatment-period and low urinary 11-nor-9-carboxy-Δ9 -tetrahydrocannabinol-level upon admission predicted the peaking trajectory of R-GMM-class-two-CWS. Withdrawal syndrome medication (PRN), comorbidity, cannabis-history data and gender balance were not significantly different between the CWS-classes. Although possibly confounded by PRN-medication, this exploratory study supports the presence of two CWS-variants in adult cannabis-dependents, characterized by a slowly decreasing (“protracted”) slope (class one) or a clear crescendo-decrescendo trajectory (class two). The latter was associated with a significantly shorter inpatient detoxification period and lower urinary THC-COOH-levels at admission.