Abstract: Some characteristics of Lake Al-Asfar were studied seasonally from May, 2008 to April, 2009. Analysis of sediment core analysis showed that, the maximum content of Zn (5.2 ppm) and Cu (2.5 ppm) were recorded at 5.0 and 25.0 cm depth, respectively. The highest value of Pb was 9.02 ppm at 1.0 cm depth. Eight fungal species belonging to 4 genera were collected from the sediment of Lake Al-Asfar. Penicillium oxalicum was the most common fungus recovered from all sections of the core up. Pythium sp. was the present at the upper section of the sediment. Marked seasonal quantitative and qualitative differences occurred in the phytoplankton communities of the lake. Five algal groups (Chlorophyceae, Cyanophyceae, Chrysophyceae, Bacillariophyceae and Euglenophyceae) were recorded during the investigation. The maximum seasonal succession was found in the spring, whereas the lowest value was occurred in the fall. The total crop densities were mainly a reflection of the trends in numbers of Chlorophyceae. Chlorella sp., Chlorococcus humicola, Oedigonium sp., Scenedsemus bijuga, Cycltella meneghiniana, Cyclotella ocellata, Fragillaria capucina, Gyrosigma sp., Navicula lanceolata, Synedra acus and Rhadomonas ovalis.