The phytotoxicity of Azolla pinnata and Lemna minor was assessed when exposed To Treated Palm Oil Mill Effluent (POME) for their survival and growth tolerance in a 5-day exposure conducted in an open laboratory at Universiti Kebangsaan Malaysia. A total of 34 100 mL-containers were used, with three replicates for each concentration, including plant less control and plant control. 50 mL of treated POME in different concentrations (100%, 75%, 50% and 25%) was filled in each container and exposed to 3 g Azolla pinnata or Lemna minor with observation conducted daily. After two days of exposure, 40% of A. pinnata died in 100% concentration and almost 100% died after 5 days of exposure for all concentrations. On L. minor, only 5% mortality was observed for 100% concentration on the fourth day and remained healthy until the end of five days. At the end of 5-day phytotoxicity exposure, the highest removals were 63.0%, 70.5%, 51.0%, 65.4% and 53.8% respectively for COD, BOD, Ammonia, Phosphate And Nitrates by A. pinnata, while the maximum removals recorded by L. minor were 61.0%, 54.0%, 9.8%, 61.4% and 31.6% respectively, giving evidence that A. pinnata is more effective in removing pollutants than L. minor although its survival in the treated POME is lesser than L. minor.