📖 The shrimp Melicertus kerathurus (Forskål, 1775) and surface water samples were collected half-monthly for 12 months from the five study sites in Mediterranean Sea of Alexandria, Egypt and Arabian Gulf (Saudi Arabia). The present study aimed to measure: 1- the monthly variations of water temperature (°C) ; transparency (Secchi disc reading in cm); total alkalinity (mg/l) ; total dissolved solids (mg/l) ; salinity (g/l) ; chlorides (mg/l); PH (mg/l) ; total hardness (mg/l) ; total Nitrogen (mg/l) and Tributyl tin (μgg-1) in Mediterranean Sea of Alexandria, Egypt (Anfoushy beach (open sea) & Abu Qir Bay) and Ad-dammam, North Khobar and South Khobar of the Arabian Gulf (Saudi Arabia). 2- Concentration of Na, Mg, Al, P, S, Cl, Cd, Ca, Fe, Ni, Cu, Zn, Ar, Hg and Pb in the sea water and gills of the shrimp Melicertus kerathurus in the five marine habitats under study to comment on the possible dysfunction of respiratory system due to pollution stress. Analysis of variance (ANOVA) , Bartlett's test for equal variances, Tukey's Multiple Comparison Test, Dunnett's Multiple Comparison Test and Newman-Keuls Multiple Comparison Test were applied.