Background: While acute pancreatitis (AP) resolves spontaneously with supportive treatment in most patients, it may be life-threatening. Predicting the disease severity at onset dictates the management strategy. We aimed to define the patients with mild pancreatitis who may be considered for outpatient management with significant cost-savings. Materials and Methods: This prospective observational study included 180 patients with mild AP according to the harmless acute pancreatitis score (HAPS) and Imrie score. The relationships of biochemical parameters with the changes in the Balthazar score and clinical course were examined. Results: The study included 180 patients (111 females, 69 males; mean age: 53.9 ± 17.2 years; range: 17–92 years). The etiology was biliary in 118 (65%) patients and remained undetermined in 38 (21.1%) patients. Computed tomography (CT) performed within the first 12 h revealed mild and moderate AP in 159 (88.3%) and 21 (11.7%) patients, respectively. CT repeated at 72 h revealed mild, moderate, and severe AP in 155 (86.1%), 24 (13.3%), and 1 (0.6%) patients, respectively. Comparisons between stages A + B + C and D + E showed significant differences in the amylase levels on day 1 and 3, and in C-reactive protein on day 3. Also, in stage D and E disease, narcotic analgesic intake, oral intake onset time, and pain were significantly higher. Conclusion: There were no significant changes in the CT findings of patients with mild AP at 12 and 72 h. Most patients (n = 179; 99.4%) recovered uneventfully. Patients with mild pancreatitis according to the HAPS and Imrie scores can be considered for outpatient management. The recovery is longer in stage D and E disease.