Autofluorescence (lambda = 530 nm) of the human lens was determined as a function of age by fluorophotometry in insulin-dependent diabetics and in healthy controls. Statistical analysis revealed a significant linear age dependency for both groups (7.98 ng eq X ml-1 y-1 for diabetic patients, P less than 0.001 and 6.36 ng eq X ml-1 y-1 for healthy controls, P less than 0.001) and a significant dependency on diabetes duration (8.78 ng eq X ml-1 per year of diabetes duration, P less than 0.001). The increase with age was found from about zero value at early childhood.