In the city of El Jadida, disposal of untreated wastewater in the ocean has a negative impact on the environment and the health of the populations who live along the urban effluents. The evaluation of parasites, such as helminths that are carried in the residual water, is a first step in understanding the health risks they engender. This evaluation requires an effective and appropriate methodology of analysis that allows the detection of helminth eggs in different environments. The parasitological makeup of wastewater in the city of El Jadida and the marine environment where it is discharged was examined. A significant level of biological pollution was detected in the main sewer of the city and in the coastal areas near the discharge points. The presence of helminth eggs at the coastal stations located further away from the overflow pipes proves that the parasitic mass can and does move. Qualitatively, Ascaris eggs were omnipresent through out the year in all the monitoring stations along the main sewer and along the coast. Thus a part of this work evaluates the risk of untreated wastewater discharge to spreading of ascariasis along the discharge area of the city. This study is a copro-epidemiological evaluation on a group of children living near the area of wastewater effluents. For a comparative approach, a control group has been selected from a neighbourhood far from the discharge area. The incidence of ascariasis was 18.1% in the study group and 1% in the control group. The risk attributable to wastewater in transmitting ascariasis to exposed children was about 17%. Boys, particularly those between the ages of 7 and 10, appeared to be the most vulnerable to ascariasis exposure. The results we obtained demonstrate that proximity to untreated wastewater poses a real health hazard.