The uptake of technetium-labelled sulphur colloid by the liver was investigated by monitoring 69 patients on a gamma camera/computer system. Following an intravenous injection 30 half-minute frames were collected and summed to give a composite view. Regions of interest were drawn round the liver and over the aorta and corresponding activity-time curves were formed. A simple physiological model has been assumed and two parameters, namely total uptake and rate of uptake, were shown to give fairly good separation between the classes of normal, cirrhosis, space occupying lesions, reticulosis and hepatitis. Furthermore the uptake rate-constant was also shown to be a useful indication of whether or not a reticulosis or hepatitis was in an acute phase. Principal components analysis was also applied to the liver curves producing two relevant components. However, a plot of the first against the second yielded no better separation of classes than that obtained by the model.