Pleurodesis is commonly indicated for symptom relief in patients with malignant pleural effusions. A number of factors may influence pleurodesis outcome, but whether tumor type is one of them is a matter of debate. This study investigates the impact of tumor type on the efficacy of bedside doxycycline and thoracoscopic talc poudrage pleurodesis in order to determine which patients may benefit most from these procedures. A retrospective study of 138 and 450 doxycycline and talc poudrage pleurodesis procedures, respectively, evaluated their overall successes and failures, according to primary tumor types. In addition, a logistic regression model addressed whether the pleurodesis outcome in different tumor types was influenced by or attributable to pleural tumor burden. In the talc group, patients with lung cancer and mesothelioma had significantly lower complete response rates (63 and 61%, respectively) as compared with breast (77%) and other metastatic effusions (74%, p = 0.012). In the doxycycline group, the data followed the same trend in that complete response rates were lower in patients with lung carcinomas (31%) than in those with breast cancer (54%) or metastases from other primary sites (74%, p = 0.001). The regression analysis showed pleural burden and tumor type as independent predictors of pleurodesis failure in the talc group. The tumor type involving the pleural surfaces influences the success of a pleurodesis, regardless of the sclerosing agent used. Malignant effusions due to mesothelioma and lung cancer are particularly prone to a failed procedure.