the multiplicative kinetics in diphasic 40% blood-agar media was studied in five clones and the parental strain of crithidia fasciculata (kinetoplastida: trypanosomatidae). the clones were obtained from cultures in 40% blood-agar and were named as ia, iiia, iva, va and caa. in each case, diphasic blood agar media with brain heart infusion broth 3,7% was inoculated with 103 choanomastigotes. the concentration of parasites were estimated weekly during 12 weeks expressing these concentrations in choanomastigotes/mm3. the variability was evaluated by anova tests for repeated measures (á:0,05). electrophoresis in polyacrylamide gel with sodium dodecil sulfate (sds-page) was also performed to evaluate the protein profiles of the clones and parental strain. the results showed a short logaritmic growth phase before a long stationary phase. there were not significant statistical differences in the concentration of choanomastigotes/mm3 between the studied systems during each day of observation (p > 0,05). the polypeptide profiles of the extracts showed highly homogeneus patrons. these results could suggest that the minor evolutive pressures that suffer naturally c. fasciculata in its propagative cycle in insects could be related to the observed homogenitiy but its needed more research in topics as inmunology, biology and genetics in order to demostrate this homogenity
