Nanofiltration (NF) of solutions containing low levels of metal ions, in the absence and presence of complexing agents, using three polyamide membranes was investigated. For a given membrane, metal rejection increased with decreasing ion concentration and valence of metal ion in the absence of complexing agents. The rejections of 20 mg/L of Co2+, Ni2+, Mn2+, Sr2+ (pH 4) were above 90% at an applied pressure of 65 psi with DK (MWCO, 150) and DL (MWCO, 300) membranes and near 15 to 20% with a GE (MWCO, 1000) membrane. In the presence of complexing agents, the rejection of metals was generally higher than those obtained in their absence. The rejection of metals increased with increasing solution pH and finally, reached a plateau beyond each certain pH value. Such pH-dependent rejections could be satisfactorily related to the overall formation constants between metal ions and complexing agents.