AbstractThis paper continues the study of fuzzy group theory which has been explored over times. We propose maximal fuzzy subgroups and Frattini fuzzy subgroups of fuzzy groups as extensions of maximal subgroups and Frattini subgroups of classical groups. It is shown that every Frattini fuzzy subgroup is both characteristic and normal,respectively. Finally, some results are established in connection to level subgroups and alpha cuts of fuzzy groups.