To know the effect of presowing seed soaking with some growth substances (kinetin, IAA, ethrel and salicylic acid) on vegetative growth and yield contributing parameters in soybean [Glycine max (L.) Merrill] the investigation was undertaken. The salient features from the study are; - All the treatments showed the enhancement effect on vegetative growth, viz. seediling emergence, germination percentage, plant height, number of leaves and branches per plant as compared with control, whereas salicylic acid delayed the seedling emergence process and lowered the germination percentage. - Nodule initiation, number of nodules and nodule weight were hastened and increased respectively under all the treatments whereas IAA showed an opposite effect on all the parameters at the early stages of nodule development. - Kinetin, IAA and ethrel showed the significant enhancement effect on the levels of biochemical parameters throughout the time of seed development whereas salicylic acid and water showed the tendency similar to that of control. - Yield and its components, viz. number of flowers, pods and seeds per plant were significant increased under all the treatments but they didn’t show any significant enhancement effect on number of seeds per pod and pod setting rate. One hundred seed weight was lower under all the treatments, indicating the dilution effect resulting from incapability of increased number and size of source to provide the increased size of sink with assimilates.