A convenient method for preparation of 5-Selenocyanatouracil (5-SeU), this compound gains importance because it is similar to 5-Fluorouracil which is one of the famous uracil derivatives as an anticancer drug. Some of invitro pharmacological activities such as DPPH antioxidant effects and antimicrobial activity, in addition to median lethal dose (LD50) were estimated. The study aimed to use a convenient synthesis procedure, and evaluation of in vitro pharmacological activity, also to determine the median lethal dose of 5-SeU. 5-SeU synthesis was carried out in very good yield through a direct reaction between 5-Iodouracil and freshly prepared potassium selenocyanate in refluxing aqueous solution to give light-gray crystalline. Antimicrobial measured by disc diffusion method. LD50was determine using Albino rats. 5-SeU compound was branded by FT-IR; 13C- NMR and 1H- NMR spectroscopic data. The results showed no antibacterial effects for most of test bacteria with a low inhibition effect on Staph. Aureus, and Pseudomonas aeruginosa, with moderate inhibition zone at candida culture.