Chronic Maxillary Atelectasis (CMA) and Silent Sinus Syndrome (SSS) are conditions that may lie on the same clinical spectrum, since both have similarities in pathophysiology, clinical findings and treatment, although the absence of sinonasal symptoms is the main difference between them. In this study we present three different cases of CMA that were submitted to functional endoscopic sinus surgery to exemplify this condition and we made a literature review about both CMA and SSS for the most relevant and recent data about the subject. Most studies show that a negative pressure gradient may be the cause for the maxillary antral collapse and that best treatment is the endoscopic approach to reopen the sinus and restore its ventilation, orbital floor reconstruction is still debatable though. In conclusion, the understanding about both CMA and SSS seem to be increasing in the last years and that allows a better treatment and classification of the these conditions.