Contarini syndrome refers to the presence of bilateral pleural effusions with different characteristics resulting from distinct aetiologies on each side. The syndrome was named after Francesco Contarini, the 95th Doge of Venice, who had right-sided transudative effusion possibly due to heart failure, and left-sided exudative effusion due to parapneumonic effusion. While bilateral pleural effusions typically exhibit similar characteristics and are secondary to the same underlying cause, such as heart failure or malignancy, there have been rare reports of bilateral effusions with different characteristics. In this case report, we present the case of a 53-year-old female with known breast carcinoma who presented with right-sided exudative pleural effusion and left-sided transudative pleural effusion, each with distinct aetiologies, thus establishing Contarini syndrome. This report highlights the importance of considering the possibility of two separate aetiologies for bilateral pleural effusions, which should not be overlooked in clinical practice.