The study examined the effects of subanaesthetic doses of ketamine on the histology of the lungs. Twenty (20) adult Wistar rats of average weight 180g were used for the study. They were assigned to five groups; A, B, C, D and E (n=4). Group A served as the control while B, C, D, and E served as the experimental groups. Group A received 0.1 ml of normal saline, Group B and C received 25mg/kg and 30mg/kg body weight of ketamine hydrochloride respectively for 5 days and Group D and E received 25mg/kg and 30mg/kg of ketamine hydrochloride respectively for 7days. After administration of the drugs for the different durations, the rats were sacrificed by 50mg/kg thiopental sodium. Aortic perfusion was done and the lungs were collected and processed for routine histological technique for Haematoxylin and Eosin (H& E) staining method. Histological sections of the lungs obtained from the experimental groups showed presence of few alveolar cells, fibrous Interalveolar spaces, and binucleate alveolar cells. Ketamine decrease in number and binucleation of the alveolar cells of the lungs. The effects were dosage and duration dependent. In conclusion, ketamine administration affected the histological integrity of the lungs therefore; use of ketamine for non-medical reasons should be done with utmost caution.