Alanine aminotransferase (ALT) is the most common and cost effective screening test for asymptomatic liver disease. There is paucity of data on normal ALT among healthy individuals in India. An observational cross sectional study was conducted from January to July 2013 to estimate the upper limit of normal for ALT in healthy south Indian population. Adults undergoing voluntary or pre-employment health screening were included. Those with current and past alcoholism or smoking, acute illness or hospitalization during preceding 12 months, non-steroidal anti-inflammatory or over the counter medication use within a month, current or past intake of herbal medications, any chronic medical illness, abnormal body mass index (BMI), fatty liver in ultrasound, abnormality in haemoglobin, platelet count, blood sugar, creatinine, lipid profile and thyroid function test and positive serology (Hepatitis B, C or HIV) were excluded. A total of 2600 subjects were screened. 344 were included for analysis. Mean age was 35 years in men and 34.83 years in women, with a mean BMI of 22.2 kg/m2 in men and 21.8 kg/m2 in women. The mean ALT in men and women were 21.87 ± 2.9 (97.5th percentile 28 U/L) and 19.35 ± 3.3 (97.5th percentile 24 U/L) respectively. In conclusion, mean and upper limit of ALT (97.5th percentile) in south Indian men was 21.87 and 28 IU/L and women were 19.35 and 24 IU/L respectively. There is a need to re-consider ALT levels in our population for better detection of individuals at risk for liver disease.