Eruptive melanocytic nevi (EMN) are characterized by the sudden onset of numerous melanocytic nevi on previously uninvolved sun-exposed area. The mechanisms of the EMN are not well understood, but have been associated with systemic immunosuppression, bullous dermatoses, and a melanocytic stimulation drug. We report a 5-year-old girl with multiple hyperpigmented maculopapules on whole body. These lesions had first appeared on the chest at 1 year old, and hundreds of lesions covering her entire skin surface had developed over the next 1 year. They were 0.5 to 3 mm in diameter, and did not look like atypical nevi clinically and dermoscopically. BRAF mutation was not found from the nevi of the patient. The patient developed EMN with the absence of associated defined, noncutaneous abnormalities. Second patient with EMN was a 42-year-old man with widespread eruptive melanocytic nevi. He had been treated for imatinib-resistant chronic myeloid leukemia with radotinib, a selective BCR-ABL1 tyrosine kinase inhibitor. Three months after treatment with radotinib, 1-4 mm sized multiple pigmented papules developed on whole body, which were diagnosed as EMN. We describe two cases with EMN in a healthy child and a chronic myeloid leukemia, who is the first reported case treated with radotinib.