The aim of this study was to determine the effects of water level (WL), hydraulic loading rate (HLR) and Nitrogen (N) variation on LAS removal in laboratory-scale vertical flow constructed wetlands (CW) units treating synthetic greywater. Four laboratory-scale vertical-flow CW units were set up by which two of them were planted with Cattails (Typha angustifolia) (CW-C1 and CW-C2) and the others were Umbrella plants (Cyperus alternifolius) (CW-U3 and CW-U4). The lab-scale CW units were operated at the same operating conditions: HLR (10 ? 30 cm/d), WL (0.3 ? 0.5 m) and N concentration (5 ? 20 mg/L).  It has been found that CW-C2 and CW-U4 units could achieve LAS removal efficiencies at 97.1 % and 96.8 % at HLR of 10 cm/d and water level of 0.64 m (0,5 m from top). The CW system could reach LAS and COD removal efficiencies of 82 ? 98 % and 78 ? 93 %, respectively. The average influent nitrogen concentration of 10 mg/L could be sufficient for plant growth and operation of CW units. While LAS is removed in CW system, it causes the increase of SO₄^2- concentrations in the effluent which could observe a maximum SO₄^2- concentration at HLR of 10 cm/d, indicating degradation of LAS. With regard to the wetland species, the research demonstrated that both species (Cattails and Umbrella) are suitable as CW plants in treating greywater. No significant difference was observed on treatment performances between the two species, but cattails showed stress at low water level and low nitrogen concentrations.