This study was carried out to investigate the effect of concurrent oral administration of aqueous leaf extract of Azadirachta indica (Meliaceae) on the pharmacokinetic properties of chloroquine sulphate in experimental rabbits. The results indicated that concurrent administration of both agents resulted in a significant decrease in serum concentration, slower absorption and elimination as well as longer half-life of chloroquine sulphate. The highest relative decrease of 78.0% was recorded 4 hours after concurrent administration, while the smallest decrease (64.6%) occurred 24 hours after concurrent administration. Significant reductions were also noted in some pharmacokinetic parameters of chloroquine and included the area under the curve (71.9%), maximum serum concentration (69.8%), absorption rate constant (37.3%), elimination rate constant (53.9%), clearance rate (76.5%) and volume of distribution (47.2%). However, there was a pronounced increase in the half-life of the drug (125.7%).