This paper is the result of the study of pigmented Euglenaceae performed within the area of the Jacuí Delta State Park, located between parallels 29º56' and 30º03'S and meridians 51º12'and 51º18'W, with qualitative samplings at 25 stations, distributed over 8 islands, 8 "sacos" (i.e. small bays), 4 river mouths, 2 stream mouths and 3 channels in December/1993 and January/1994, and from February/1998 to December/1999. One hundred and fifty taxa of the Euglenophyceae were identified in the area. Currently 23 specific and infraspecific taxa of genus Euglena and 12 taxa of Lepocinclis are presented. E. acus Ehr. var. acus, and L. salina Fritsch var. salina were the taxa best represented in the region since they occured in over 40% of the samples studied. E. bonettoi (Tell & Zaloc.) Couté & Thérez., L. playfairiana Defl. var. striata Conf. and L. caudata (Cunha) Conr. were recorded exclusively for South America; sixteen taxa identified have a cosmopolitan distribution. Ranges of some abiotic variables of the environments in which each taxon occurred in the study area are mentioned.