© 2018 Elsevier Inc. Most renal masses in the United States are incidentally detected via abdominal imaging. This has led to an increase in the incidence of small renal masses (≤4 cm). Active surveillance is, an oncologically safe option in slow growing and indolent tumors in other organs and has recently become more widely studied in small renal masses. For selected patients, particularly those who harbor significant comorbidities, active surveillance is a safe option for small renal masses. Renal biopsy may be helpful in the decision making process, but remains an optional component for the active surveillance of small renal masses.