Aim. To investigate the incidence of sleep-related breathing disorders (SRBDs) in patients with active acromegaly (AM), to specify risk factors influencing apnea/hypopnea index (AHI), and to reveal the specific features of obstructive sleep apnea (OSA) in patients with AM versus those with OSA without AM. Subjects and methods. Fifty patients with active AM were examined and divided into 3 groups: control group 1 did not differ from the study group in body mass index (BMI); control group 2 did not similar in AHI from the AM group. Polysomnography was done in all the patients. Results. SRBDs were detected in 40 (80%) patients. Obstructive apnea was found in all cases. Correlation analysis revealed the relationships between AHI and gender (AHI was higher in the men), BMI, disease duration, and insulin-like growth factor 1 (IGF-1). There were no correlations between AHI and gender, maximum adenoma size, and growth hormone levels. Compared with control group 1, the AM group had a statistically significantly higher median AHI [16 (1—92) and 4.7 (0—31.3) episodes per hour of sleep (p<0.001)]. In control group 2, the median BMI was considerably higher than in the control group [29.2 (19.9—44.3) and 35 (24—56) kg/m2 (p<0.001). Conclusion. The detection rate of SRBDs in patients with active AM was 80%, with obstructive disorders being prevalent. There was a positive relationship between SRBD severity and BMI, AM duration, IGF-1 level. Compared to the controls, the patients with AM developed SRBDs similar in severity with lower BMI; severer SRBDs were detected in the patients with active AM with the similar BMI.