Alopecia areata (AA) is an autoimmune disease, manifesting as non-scarring hair loss. Here we report a 57-year-old woman, who presented with sudden diffuse non-scarring hair loss on the scalp. Histology confirmed the diagnosis of AA. Imaging studies revealed the presence of an irregular mass in the left kidney, and histology demonstrated spindle cell-type renal cell carcinoma. There was spontaneous regrowth of hair after surgical and chemotherapy treatments. Reports of AA as first manifestation of malignancy are uncommon, and to our knowledge, this is the first report of AA as a paraneoplastic manifestation of renal cell carcinoma. This report also suggests that screening for malignancy should be considered in older patients, who present with sudden and diffuse AA.