objectives: to estimate the percentage of patients with overactive bladder (ob) attending urology or gynaecology outpatient clinics who show associated diseases which complicate their clinical state and quality of life. methods: this is an epidemiologic, cross-sectional and multi-centre real world trial. 1,659 patients with ob were studied in urology or gynaecology outpatient clinics. demographic data, anthropometric data, presence of chronic diseases (hypertension, diabetes, cerebrovascular disease, ischemic cardiopathy, chronic obstructive pulmonary disease, cognitive damaged, cataract, movement disability and constipation), presence of associated diseases (falls, lower urinary tract infections, genital skin infections, depression, sexual dysfunction and sleep disorders), presence of urinary incontinence symptoms and impact on quality of life according to iciq-ui sf score. results: mean age (s.d) of studied sample was 59.2 (12.9) years and 73.6% were female. most patients lived in urban settings (67.3%), had primary studies or less (56.8%) and had active work or at home work (66.2%). most frequent diseases associated to ob were genital skin infections, lower urinary tract infections and sleep disorders. sexual dysfunction was more frequent in males than in females; lower urinary tract infections, genital skin infections and depression were more frequent in females than in males. patients with these diseases showed higher iciq-ui sf scores than patients without them, indicating higher impact. conclusions: presence of associated diseases in patients with ob is frequent in males and females and it is associated to higher impact in patients' life. it seems relevant to pay attention in detecting them through the medical history of patients consulting about ob or urinary incontinence symptoms.