Ptosis is a common complaint in patients who refer to ophthalmologists especially oculoplastic surgeons. Occasionally, ptosis may be the presenting sign or symptom of a systemic disease. Therefore, it is of great importance to know the causes of ptosis, its clinical presentation, and the systemic evaluation that one must undergo before going into surgery. This review presents the common causes of ptosis according to age of appearance, systemic diseases that must be ruled out, and the surgical options that exist.