Diseases of the male genitalia range from infectious lesions to inflammatory and neoplastic conditions, including many genital manifestations of more general skin diseases. This review highlights the clinical features, diagnosis and treatment of the most common dermatoses of the male genitalia. Herpes genitalis and infections caused by human papillomavirus (HPV) are increasing, particularly in young sexually active people. Herpes simplex virus infection is the commonest infectious cause of genital ulceration, with evidence that many infections are asymptomatic. HPV infection may be latent, subclinical and clinical. The most common causal agents for condyloma acuminatum are low-risk HPV 6 and 11; high-risk HPV types 16 and 18 are associated with premalignant and malignant lesions. Treatment for genital warts remains unsatisfactory; recurrences are common. Imiquimod, a new topical immunotherapeutic agent, which induces interferon and other cytokines, has the potential to be a first-line therapy for genital warts. Scabies and pediculosis are transmitted by skin-to-skin contact and sexual transmission is common, with the penis and scrotum favourite locations for scabious lesions. Oral ivermectin, a highly active antiparasitic drug, is likely to be the treatment of choice, but until approval is granted it should be reserved for special forms of scabies. Common skin diseases, e.g. psoriasis and lichen planus, may have an atypical appearance in the genital area. The typical psoriatic scale is usually not apparent because of moisture and maceration. Allergic contact dermatitis of the genital area may result from condoms, lubricants, feminine hygiene deodorant spray and spermicides. More often, contact dermatitis is irritant, resulting from persistent moisture and maceration. Lichen sclerosus is a chronic inflammatory disease that occurs as atrophic white patches on the glans penis and foreskin. The penile form is a common cause of phimosis in uncircumcised men; involvement of the urethral meatus may lead to progressive meatal stenosis. Plasma cell balanitis is a benign, idiopathic condition presenting as a solitary, smooth, shiny, red-orange plaque of the glans and prepuce of a middle-aged to older man. Squamous cell carcinoma (SCC) in situ, e.g. erythroplasia of Queyrat and Bowen's disease, cannot be excluded clinically; their apparent clinical benignity may lead to lengthy periods of misdiagnosis and biopsy is required to confirm the diagnosis. SCC is the most common malignancy of the penis and the role of oncogenic HPV-types has been also established in SCC of the penis. Prevention of SCC of the penis presupposes an identification of risk factors, early detection of all pre-cancerous lesions and treatment of phimosis.