The aim of the current study was to determine the presence of heavy metals (lead, cadmium, copper, and zinc) in three wastewater treatment plants at different locations in Sharkia Governorate, Egypt and its concentration compared with its natural level by following American Public Health Association strategies using atomic absorption spectrophotometer. Thirty wastewater samples were collected from wastewater before treatment (input) and treated wastewater (output) (15 samples of each) from Abo-Hammad, Diarb-Negm, and Al-Kenayat wastewater treatment plants. Total mean values of lead, cadmium, copper, and zinc in the input wastewater were 6.33±0.83, 1.09±0.12, 3.73±0.49 and 3.16±0.39 ppb, respectively while from output wastewater samples, respective values were 3.22±0.58, 0.49±0.09, 1.79±0.33, and 2.77±0.74 ppb. Lead and cadmium ions showed higher values above their natural level. Concerning copper, about 53.3% above its natural level while zinc concentration was within the natural level in all input and output samples. Diarb-Negm plant, which follows the Kroger technique, was the highest wastewater treatment plant in the removal of lead (57.1%), cadmium (75%) and copper (79.4%). While zinc removal percentage was highest (24%) in Abo-Hammad wastewater treatment plant which follows the trickling filter technique rather than other investigated plants. So the kroger technique is better than trickling filter technique in heavy metals removal. Keywords: Heavy metals, Wastewater, Atomic absorption spectrophotometer, Trickling filter technique, Kroger technique.