Bruise or contusion is the extravasation of blood in subcutaneous tissue due to rupture of blood vessel causedby impact trauma. The timing and sequence of colour changes of bruises have been known for over 100 years inforensic medical data and they are used as markers in physical abuse cases. Bruise often induces pain whentouched. Sometimes, bruise can be serious leading to other life threatening forms of hematoma.Bruises are typically caused by blunt force trauma, linked with epidermis, dermis and subcutaneous layer of theskin. Capillaries of the subcutaneous tissue have the major contribution to the formation of bruise. Extravasatedblood will spread along any line of cleavage in the tissue producing a discoloured area. Bruise formationdepends on number of factors: age, sex, site of impact, force of impact, gravity shifting, skin colour anddiseases. Bruises are more clearly visible on fair skin as compared to dark skin. After how much time thediscolouration of bruise starts, depends on the severity of the injury. Deep bruises take several hours or evenseveral days to appear. Elderly and children bruise more easily. Bruise occurs more readily in the loose tissuesand the tissues having large subcutaneous tissue as compared to the skin which is supported by fibrous tissue. Abruise which shows the pattern of the impacted object is said to be patterned bruise. The pattern of the bruisecan be used to determine the causative object or the photograph of the injury and the object can be determined.Age determination of bruise has medico-legal importance. A fresh bruise is tender and slightly raised above thesurface and shows some swelling when compared to the other limb of the body. The age of bruise is oftendetermined by the colour of the bruise. This colour change in the bruise is due to the changes in haemoglobinpresent in the blood. Red colour in the bruise is caused by haemoglobin released from the ruptured bloodvessel. Purple/blue colour is caused by the extravasation of the deoxygenated venous blood into interstitialvessel. Macrophages attached to the site of injury degrade the haemoglobin into biliverdin which accounts forgreen colour. Biliverdin is quickly degraded into bilirubin, which accounts for the yellow colour of the bruise,often seen in healing process. The iron contained in haemoglobin combines with ferritin and formshaemosiderin, which accounts for the brown colour in the bruise. Colour of bruise is light at the centre becausereleased blood is pushed outward by the impact.Age of bruises can be determined by number of methods. In Direct gross examination (Histopathologicalexamination), large amount of information can be obtained from body in mortuary. While assessing the age ofbruise, location of bruise, size of bruise, age and health of victim are taken into account for correct assessment.Colorimetry method of age determination works on the principle of human eye that interprets the pigmentationof an image by calculating the amount of light, as well as proportions of its constituents red, green and bluecolours. This technique is easy, fast, non-invasive and gives reproducible results. In gross naked eye andphotographic assessment, bruises are determined on the basis of their appearance in the photographs. Another2method for estimating age is microscopical examination in which presence of various components of blood andtheir products such as biliverdin, bilirubin, Haemosiderin, haemoglobin, leukocytes etc are studied.Histochemical method of age estimation involves detecting the activity of various chemicals such as aminopeptide, alkaline phosphatase, amino phosphatase in the bruise area to assess the age. Spectrophotometry isanother non invasive method of age estimation. It works on the principle that different substances absorb,reflect or emit light in different ways. Colour change can be measured using this technique.