Relationship between Wiener's index--a distance-based topological descriptor and multidrug-resistance-associated protein (MRP1) inhibitory activity of pyrrolopyrimidines and their derivatives has been investigated. A dataset comprising of 82 analogues of pyrrolopyrimidine was selected for the present study. The values of Wiener's index were computed for each of the 82 analogues using an in-house computer program. Resultant data were analyzed and a suitable model was developed after identification of the active range. Subsequently, a biological activity was assigned to each analogue involved in the dataset using this model, which was then compared with the reported MRP1 inhibitory activity. Accuracy of prediction was found to be 88% using model based on Wiener's index.