This study was projected to find out the prevalence of depression, anxiety and stress in patients with non-communicable diseases having follow-up in Black Lion Specialized Hospital and investigate certain predictor variables behind the negative mental states. This cross-sectional study comprised of a sample of 382 patients with confirmed non-communicable diseases selected via convenience sampling technique. The data was collected using interview based structured questionnaires, after taking informed consent, from 16th January to 2nd April, 2019. Levels of depression, anxiety and stress were gauged using the short version of the Depression Anxiety Stress Scales (DASS)-21. The study findings revealed that significant proportion of the studied respondents had mild to severe levels of depression, anxiety and stress scores, with a prevalence of 38.2 %, 51.6 %, & 27.7 %, respectively. There was no statistically significant difference between the two types of non-communicable diseases studied. The strongest predictors for high depression, anxiety & stress scores among diabetic and hypertensive patients were marital status and clinical stage of the disease, each with p value