Excessive surface water nitrogen loading can affect fresh and marine water quality and cause ecological damage to the aquatic environment. Using constructed wetlands (CWs) to treat a range of wastewater and non-point sources containing high N could be a viable option in many cases. However, the nitrogen removal effect of wetlands is strongly influenced by temperature and season. In this study, the effect of temperature and season on nitrogen removal in Ekeby wetland was analysed using data from Eskilstuna Energi och Miljö. On average total nitrogen removal in the vegetated period accounted for 70.3% of the total removal, while during the non-vegetated period it was only 29.7%.The average TN removal during the spring growth period accounted for 44% of the removal during the vegetated period whereas the avergae TN removal during the autumn growth period accounted for 38%. Linear regression analysis after removal of outliers resulted in R²_adjusted = 0.409, showing that about 40% of the nitrogen removal can be explained by temperature.