Dry eye is a multifactorial disease and hence single test cannot diagnose dry eye. Diagnosis of dry eye needs careful assessment of the symptoms along with battery of investigations. Many questionnaires have been developed to assess the symptoms of dry eye disease (DED). Some of the important questionnaires are Ocular Surface Disease Index (OSDI), Dry Eye Questionnaire (DEQ-5), Impact of Dry Eye on Everyday Living (IDEEL), National Eye Institute’s Visual Function Questionnaire (NEI VFQ-25) and Dry Eye-Related Quality-of-Life Score (DEQS). Investigations for dry eye mainly target on the tear secretion, tear clearance, tear volume, tear film stability, tear evaporation, ocular surface damage, lipid layer of the tear film, chemical properties of the tear film and inflammation of the ocular surface. There are many investigations that target on the above parameters and helps in accurate diagnosis of Dry eye disease (DED).