Spontaneous esophageal perforation into the pleural cavity (Boerhaave's syndrome) is a rare life-threatening condition, which requires early diagnosis and urgent management. The diagnosis of such critical condition in many cases is delayed because of atypical clinical presentation, resulting in increased morbidity and mortality. Cytological examination of pleural fluid can provide early, fast and accurate diagnosis of such critical condition and help in better and early management of this disease. We describe a case of an 81-year-old female with esophageal perforation who presented with a left sided pleural effusion. The correct diagnosis was established in this case by observing gastrointestinal-like fluid characteristics of the thoracic drainage upon cytological and chemical analyses and the rupture was confirmed by esophagography. The cytological examination of pleural fluid revealed benign reactive squamous cells, fungal organisms, bacterial colonies, and vegetable material consistent with a ruptured esophagus. Cytological examination of pleural fluid is a rapid and accurate technique that can help in establishing the diagnosis of this challenging entity and guide initiation proper management of this unusual entity.