This research work was carried out to determine the effect of Acanthus montanus on fasting blood sugar level of adult wistar rats. Twenty wistar rats (both male and female) weighing between 140g to 160g were used for this research project. They were acclimatized for 14 days after which the animals were grouped into four groups of five rats each. Each animal were administered based on their body weight. The dose given to animals in group A was 300mg/kg body weight of Acanthus montanus, Group B was given 500mg/kg body weight of Acanthus montanus, Group C was given 700mg/kg body weight of Acanthus montanus and group D (control group) was given distilled water. The administration lasted for thirteen days. A day before the animals were tested for fasting blood sugar level, food and water was withdrawn and they fasted for twelve hours. Blood samples were collected from the tail of the animals and the fasting blood sugar of each of the animals was tested.