The incidence of small renal masses that are detected incidentally is increasing, particularly in patients who are in advanced age and with increased comorbidities. We review the available data on the nature and natural history of these small renal tumors, and observe that based on the limited available information, most of these lesions appear to grow slowly. We also review the currently available markers of tumor progression. We postulate that because of tumor heterogeneity, it is unlikely that advancement in prognostic knowledge will be gained using current approaches, such as histologic characteristics and tumor size, and that there is a clear need for new biomarkers. We conclude that expectant management is a viable and safe option for the patient with a short life expectancy but potentially unsafe outside a well-controlled clinical trial in the younger and fit patient.