We report a rare case of right primary testicular actinomycosis presenting as multiple testicular lesions mimicking a metastatic tumor in a 71-year-old patient with gastric adenocarcinoma. Preoperative diagnosis is difficult. The enlarged and inflamed testis was removed by orchiectomy and testicular actinomycosis was diagnosed after pathological examination. The patient had not received any further antibiotic prescription and there was no recurrent or other site involvement after orchiectomy. We illustrate this case, though it is rare, to alert pathologists and clinicians to the possible occurrence of primary testicular actinomycosis mimicking metastatic lesions in a cancer patient. To diagnose, extensive sampling of the tissue specimens may be needed. We also reviewed the published literature and found that the treatment of choice for testicular actinomycosis was orchiectomy. The usage of penicillin after orchiectomy does not seem to affect the outcomes of the disease.