Background. Minimally invasive parathyroidectomy (MIP) using local/regional anesthesia has become an accepted treatment for selected patients with primary hyperparathyroidism (HPT) and can be performed in the ambulatory setting. Methods. From 1999 to 2004, 139 consecutive patients at our institution with HPT caused by a single localized parathyroid adenoma underwent MIP through a 2.5- to 3-cm incision. Anesthesia included preoperative local/regional blocks with moderate intravenous sedation. Patient follow-up data were reviewed retrospectively. Results. All 139 MIP patients had biochemical HPT and a single adenoma localized by sestamibi scan alone (n = 119; 86%) or combined with other imaging (n = 20; 14%). The mean adenoma size was 1,184 ± 1,091 mg. Total calcium and parathyroid hormone levels were 11.3 ± 0.8 mg/dL and 451 pg/mL preoperatively, respectively, decreasing to 9.4 ± 0.6 mg/dL and 34 pg/mL postoperatively, respectively. Of MIP cases, 117 (84%) were completed with local/regional anesthesia, and 22 (16%) used general anesthesia (4 local/regional conversions). The mean operative time when reported was 56 ± 21 minutes (n = 28). Same-day discharges occurred for 120 (86%) patients, whereas 16 patients were observed overnight and 3 patients were observed for 48 hours. Operative cure was achieved in 137 (98.6%) patients (follow-up period, 15.2 ± 12.4 mo) with 1 morbidity (0.7%). Conclusions. Outpatient MIP is safe and effective in selected patients. A low morbidity (0.7% in this series), rapid recovery, and high biochemical cure rate (98.6%) parallels 4-gland exploration under general anesthesia.