Abstract: Forty nine of 50 slender-billed gull (Larus gene collected from AI-Rames coast of Al-Qateef in eastern province of Saudi Arabia were infected with one or more of nine species of trematodes belonging to 7 families. Individual birds contained 1-6 species (mean 4 species, SD=1.6.), Heterophyopsis sp was the most common species occurring in 98% of birds examined, Prevalence of other trematodes were: Cotylorus sp, 70%; Carcarioides aharonii, 60%; Parorchis acanthus, 40%; Philophthalrnos gralli, 34%; Ornithobilharria inreanedia, 20%; Pschytrema calculus, 10%; Dietziella cfeparcum, 6% and Dipolosromum spathaceum, 4%. All trematode species are reported far the first time from Saudi Arabia and also as new host record except for D. spathaceurn. The high species richness, low abundance and diversity of the helminths as compared to those of other gulls reported from other parts of the world reflect the specialized non selective diet of slender-billed gull.