Nowadays antibiotics are used on a large scale in veterinary and human medicine to cure or prevent diseases. Some antibiotics injected into hatching eggs to eliminate pathogens and prevention of egg transmission of disease. Adverse effects of drugs have always been a major concern. There is scantly information available about the safety and pathological alterations of lincosamide-aminocyclitol compounds in embryo. The objective of this study was to investigate using of various dosages of Linco-spectin solution for in ovo administration in chicken embryo. Fertile chicken eggs were divided into six equal treatment groups as follows: group 1: uninjected group. Group 2: needle-injected group; the needle was inserted into the yolk sac without any injection. Group 3: phosphate buffered saline-injected group; whose individuals were injected with phosphate buffered saline. Groups 4, 5 and 6 whose individuals were injected with linco-spectin solution at a dosage of 10 mg lincomycin and 20 mg spectinomycin or 15 mg lincomycin and 30 mg spectinomycin or 20 mg lincomycin and 40 mg spectinomycin per Kg egg-weight, respectively. Embryos were re-incubated post-treatment and allowed to develop until day 18 after which; they were examined for macroscopic and microscopic lesions. Results showed that embryos were normal in all treatment groups. Microscopically, no lesions were also diagnosed in tissues. Based on macroscopic and microscopic findings, it is concluded that linco-spectin at above-mentioned concentration is not toxic for the chicken embryo. So, linco-spectin egg-injection can be used toeliminate pathogens and prevention of egg transmission of the diseasewithout any adverse effect.