Chrysichthys auratus was collected from River Nile at Giza province during the period from the being of June 2003 till the end of May 2004. Prevalence of Trypanosoma mansouri was determined using a haematocrit centrifuge technique (70%) and percentage of haematocrite was recorded. Parasitaemia was estimated by counting trypanosomes in 30 fields ( 10 ocular x 10 objectives) of wet preparation. Individual fish carrying heavy and medium infection were most common in summer and spring respectively. Seasonal changes showed high prevalence in summer (100%). Spring (92%) and autumn (60%) and comparatively low in winter (28%). In vitro, Cultivate the Trypanosome mansouri have been attempt in uniphasic sheep blood agar medium. Minimum Essential medium (MEM)contains no serum and in MEM supplemented with 10% foetal bovine serum. During 7 days from initial inoculums growth of trypanosome was followed up in culture media. Medium containing no serum failed to support the growth of parasites and growth on uniphasic blood agar not continued after 5 days.