Algae are heterogenous, polyphyletic assemblage of very simple, water loving, autotrophic organism having no sterile layer of jacket-cells around their reproductive organs and lacking true embryogenasis. As primary producers, they are an important component of aquatic ecosystem, being inhabitants of moist freshwater, brakish water and marine environments of our biotope. The emerging picture of the freshwater algal flora of Pakistan revealed lack of information about detailed taxonomic description and systematic account of green algae from this area. Therefore, a wide-range research program was developed to make a detailed investigation on the taxonomy of green macro-algae inhabiting the freshwater environment of various districts of the Punjab and certain areas of Khyber Pakhtoonkhwa and Azad Kashmir. Among green algae, those belonging to the phyla Chlorophycota (grass-green algae), Charophycota (stone wort algae) and Vaucheriophycota (yellow-green algae) were selected for the present study.