Twenty free-ranging adult African elephants (Loxodonta africana) in northern Botswana were immobilized with a mean (±SD) of 9.5 ± 0.5 mg etorphine hydrochloride and 2,000 IU hyaluronidase by intramuscular (IM) dart. The mean time to recumbency was 8.7 ± 2.4 min. All animals were maintained in lateral recumbency. The anesthesia monitoring protocol included cardiothoracic auscultation; palpation of auricular pulse for quality and regularity; checking of rectal temperature, and monitoring of respiratory and heart rates. Results of basic physiologic measurements were similar to those of previous field studies of African elephants immobilized with etorphine or etorphine-hyaluronidase. In addition, continuous real-time pulse rate and percent oxygen saturation of hemoglobin (SpO₂) readings were obtained on 16 elephants with a portable pulse oximeter. Duration of pulse oximetry monitoring ranged from 3 to 24 min (mean ±SD = 8.2 ± 4.8 min). Differences between minimum and maximum SpO₂ values for any given elephant ranged from 1 to 6 percentage points, evidence for relatively stable trends. The SpO₂ readings ranged from 70% to 96% among the 16 elephants, with a mean of 87.3 ± 2.8%. Fifteen of 16 elephants monitored with a pulse oximeter had mean SpO₂ values ≥81 ± 2.4%, with 11 having mean Sp SpO₂ values ≥85 ± 1.5%. All 20 animals recovered uneventfully following reversal: diprenorphine at 23.3 ± 1.5 mg intravenous (IV) with 11.7 ± 0.5 mg IM, or 24 mg diprenorphine given all IV.