It has been suggested that the high prevalence of obstructive sleep apnea (OSA) in resistant hypertension (RHT) may be related to the high prevalence of primary aldosteronism (PA) in patients with RHT. It has been also hypothesized that the relationship between aldosterone and OSA might be bidirectional. In patients with RHT, it has been shown that aldosterone levels correlate with severity of OSA and that blockade of aldosterone reduces the severity of OSA. It has been postulated that aldosterone worsens OSA by promoting accumulation of fluid, which shifted in the supine position to the neck, contributes to increased upper airway resistance. Also there is growing data that PA is more frequent in patients with OSA and that the treatment of PA positively influences OSA course. Also in some studies it has been shown that patients with OSA are characterized by higher aldosterone levels and higher prevalence of PA than patients without OSA and that causal treatment of OSA might decrease aldosterone levels. Moreover, the recent guideline of the Endocrine Society on management of PA recommends to screen hypertensive patients with OSA for PA.