We present a 64-year-old patient with a 9-cm firm, irregular penile mass associated with phimosis, erectile dysfunction, and voiding difficulty. After he reluctantly admitted to multiple penile mineral oil self-injections for enlargement, surgical excision was performed. Pathologic examination was consistent with mineral oil granuloma (paraffinoma). Within several weeks after surgery, his erectile dysfunction and voiding complaints resolved. Paraffinomas have been encountered with the use of various oily substances injected for cosmetic purposes. Despite early warnings, these agents continued to be used to treat conditions ranging from hemorrhoids to wrinkles and even baldness. Fortunately, most of these fads have been abandoned by medical professionals, but the complicating lesions have been documented as having lag times as long as 30 years. Complete surgical excision remains the treatment of choice to prevent recurrence. Increased public awareness is needed for the prevention of this physically and psychologically debilitating problem. (J Am Acad Dermatol 2001;45:S222-4.)