A 70-year-old Japanese female with lepromatous leprosy developed squamous-cell carcinoma within a long standing area showing solar keratoses on her head. Alopecia had been present at least for the preceding 34 years on her forehead and frontal area of the head, and solar keratoses had existed at least for the previous 9 years. Skin smear examination for acid-fast bacilli which had continually been negative for the previous 2 years (during which 8 examinations were done) became positive. We assume that there may be some relationship between the onset of the tumor and the positive skin smear examination, although the exact connection remains unclarified.