The present study aimed to assess the diversity and distribution of Mollusca under the impact of some physico-chemical variables in Lake Nasser, Egypt. Bottom fauna was sampled for 4 seasons in 2013 and 2 seasons (winter & summer) in 2015 from the main channel of Lake Nasser and two main of its khurs (Dahmit Khur and Tushka West Khur).The study revealed the predominance of gastropods over bivalves. A total of 10 taxa of freshwater molluscs were recorded, 7 species from Gastropoda and 3species of Bivalvia representing 95 % and 5% of the total population density of molluscs respectively. Numerically, Valvata nilotica was the most abundant taxa followed by Gyraulus ehrenbergi. Melanoides tuberculata and Bulinus truncatus. Spharium simile and Pisidium pirothi showed less frequent appearance, whereas Cleopatra bulimoides and Corbicula fluminalis were recorded as rare taxa. Relationship between the total number of individuals of molluscs and environmental parameters were determined by Canonical Correspondence Analysis (CCA). The results of analysis revealed a significant correlation between the total number of Mollusca and some environmental parameters, such as dissolved oxygen, pH, depth, transparency. Additionally, Ferrissiasp. was firstly recorded from Lake Nasser.