Aims and Objective: Aspirin a non–steroidal anti–inflammatory drug having antipyretic,analgesic and anti–inflammatory actions.It is also used in prevention of myocardial infarction.However its effect on the lungs of developing embryo has not been explored yet.

Material and methods:Aspirin was given to pregnant mice in the dose of 100mg/kg body weight and the lungs of 19^th day fetus was studied for any microscopic changes.

Results:Aspirin induced rupture of alveolar lining to produce large haemorrhagic lacunar spaces. Aggregation of lymphocytes can be seen interspersed between the pneumocytes as well as in the interalveolar connective tissue space. Necrosis of  cells has lead to clumping of cells.

Conclusion:Aspirin has toxic effects on lungs of developing embryo so should be used with caution in pregnancy.