Diterpenoid 3-epicaryoptin (C26H36O9) is abundant in leaves of Clerodendrum inerme, a traditionally used medicinal plant, having insect antifeedant activities. Here, we aim to explore its cell cycle delay and cytotoxic effects in Allium cepa root apical meristem cells. Allium cepa roots were treated with 3-epicaryoptin and colchicine for 2, 4, 4+16 h (4 h treatment followed by 16 h recovery) and the induced cell cycle delay and cytotoxic effects were analyzed. The highest metaphase cells frequency for 3-epicaryoptin and colchicine treated samples were found to be 66.2% and 82.35% respectively at 4 h treatment. Treatment of 3-epicaryoptin and colchicine increased the aberrant cells %, CA, MN, c-metaphase, and PP cells. Therefore, indiscriminate use of C. inerme in traditional medicine should be restricted and the cell cycle delay and cytotoxicity inducing effects of 3-epicaryoptin needs further exploration for its cancer chemotherapeutic applications.