This study determined the pharmacokinetics (PK) of figitumumab and its effects on insulin-like growth factor (IGF) axis-related biomarkers, following a single intravenous dose (10 [n = 16] and 20 [n = 12] mg/kg) in healthy adults. Serial blood sampling for PK and biomarkers was conducted up to 84 days postdose. A dose increase from 10 to 20 mg/kg led to 1.9- and 2.4-fold increases in mean Cmax and AUC∞, respectively. Median disposition half-life was 21.1 and 27.8 days at 10 and 20 mg/kg, respectively. At 10 and 20 mg/kg, figitumumab increased total IGF-1, free IGF-1, IGF binding protein (IGFBP)–3, and insulin by 4.1- and 4.8-, 8.3- and 12.1-, 2.4- and 2.9-, and 7.3- and 9.8-fold, respectively; increases were sustained throughout the 84-day period. There was a slight and transient elevation in IGF-2. Mean plasma glucose increased by 18% and 16% at 10 and 20 mg/kg, respectively. Most treatment-related adverse events were mild in severity; the most common included dry eye (n = 9) and ocular hyperemia (n = 9) in the 20-mg/kg group. No antidrug antibodies were detected. Overall, figitumumab (10 or 20 mg/kg) demonstrated PK properties typical of IgG2 antibodies and produced substantial and sustained increases in IGF-1 (total and free), IGFBP-3, and insulin.