A field experiment was conducted at experimental farm, college of Agriculture, University of Anbar, Abu Ghraib (Alternative Site) during the summer season 2016 in silty clay loam soil to study the effectof foliar application with thiamin B1 on plant content of  HCN (hydrocynic acid) of ten sorghum cultivars, the layout of experiment was  randomized complete block design (RCBD) with three replicates , the first factor consisted of ten cultivars of sorghum (Inkath, Rabih, Kafir, Mabrouk, Buhooth 70, Syrian cultivar, Babil , Warka, Lilo and Ishtar),the second factor was three concentrations of vitamin B1 (thiamine), The plants was cut three timesduring growth season at 50% flowering to estimate the plant content of HCN, the results of this experiment are summarized as follows: the concentrations of HCN in the cultivars samples was safe levelswhen the three cuttings operationsat 50% flowering, Ishtar cultivar gave the lowest concentration of HCN was 93.3, 103.6, 118.4 ppm, at  three cuttings respectively, In addition,spraying of vitamin B1with 75 mg.L^-1concentration  gave the lowest average content ofHCN 99.1, 107.8 and 119.7 mg .L^-1at  three cutting respectively , the interaction between the study factors had a significant effect on plant content of (HCN) at the three cuttings.