Aim: The study aimed at assessing the quality of sleep in seniors. Another objective was to determine the impact of gender, age, type of residence and taking sleeping medication on the quality of sleep. Design: A cross-sectional study. Methods: Data were collected using the standardized Pittsburgh Sleep Quality Index (PSQI) questionnaire. The sample comprised 146 seniors living in the Moravian-Silesian Region, Czech Republic. The survey was conducted from January 2014 to the end of October 2014 in a long-term chronic care department of a selected hospital, two retirement homes and among seniors living in their own homes. Results: Thirty-five (24%) seniors had their global PSQI scores of 5 (i.e. the highest score indication good sleep quality) or less. The remaining 111 (76%) participants were shown to suffer from impaired sleep quality as their global PSQI scores were 6 or higher. There were statistically significant differences in component scores between seniors with the global PSQI scores of 5 or less and those with higher scores. The best quality of sleep was observed in females, seniors in the 65–74 age category and those sharing their own homes with their spouses or partners. Conclusion: Subjective sleep quality assessment varies significantly with respect to gender, age, type of residence and use of sleeping medication. Keywords: sleep quality, PSQI, subjective assessment, senior.