The present study investigated the acute and subacute toxicity of Diakyur, a polyherbal antidiabetic formulation, in experimental animal models. Diakyur contains aqueous extract dry powders of Cassia auriculata, Gymnema sylvestre, Mucuna pruriens, Syzygium jambolanum, Terminalia arjuna, Salacia reticulata, and a crude powder of Cassia javanica. The raw materials were standardized by gravimetric, HPLC and High performance thin layer chromatography (HPTLC) methods for their respective bioactive marker compounds. In an acute toxicity study, Diakyur was administered orally at doses ranging from 100-12800 mg/kg p.o. and the animals were observed for any toxic symptoms up to 72 hr. The results indicated there were no toxic symptoms up to the dose level of 12800 mg/kg p.o. In a subacute toxicity study, Diakyur was tested at the dose of 1600 mg/kg p.o. once daily for 28 days. The animals were sacrificed on the 29th day and various blood biochemical parameters were measured. The liver, kidney, heart, adrenals, pancreas and uterus were processed for histopathological study. The results of the 28 day subacute toxicity study did not show evidence of any changes in body weight, food and water intake, hematological parameters, liver and kidney function tests when compared with the control animals. The vital organs of animals treated with Diakyur for 28 days did not show any histopathological evidence of pathological lesions. From the results it is concluded that Diakyur at the dose of 1600 mg/kg p.o. is safe for long-term treatment in diabetic conditions.