The study was undertaken to assess the CT density of the antibiotics solution. CT scan of six antibiotics solution-streptomycin, chloramphenicol, Na-penicillin, ampicillin, kanamycin and cefamezine-in concentration of ablout 33% (approximately single dose of intramuscular injection) was prformed, using plastic syringes. Various concentrations of streptomycin, chloramphenicol and Na-panicillin were also examined for evaluation of relation between concentration and the CT density of the antibiotics. In addition, relationship between CT number and mathematically calculated effective atomic number and electron density of the antibiotics was evaluated. The results are as follows: 1. The CT densities of all antibiotics reveal high density (CT number 80-150) in concentration of single intramuscular injection dose. 2. CT number of streptomycin, chloramphenicol and Na-penicillin gradually increased with increased with increase of concentration of t e antibiotics, producing linear proportion to concentration, effective atomic number and electron density of the antibiotics. 3. Thereore, density of antibiotics should be included in differential diagnosis when high density on CT scan is observed.