Background: There is limited information available on the use of PIP medication in older adults having psychiatric illness. Objective: To determine the prevalence of PIP medications, and assess its predictors in older adults with psychiatric illness. Methods: A cross-sectional study was carried out at a tertiary care hospital on 456 patients of either sex, with a median age of 65 years attending the psychiatry outpatient department. Evaluation of PIP medication was done using Beers criteria 2019 and STOPP criteria 2015. Bivariate logistic regression was used to find out the predictors of PIP prescribing. Results: Results of the study reflect that a staggering number of older adults, (more than 91% and 73%) out of total of 456 patients were prescribed with at least one PIP medication identified by Beers criteria and STOPP criteria, respectively. Long-acting benzodiazepine (LABZD) like clonazepam was identified as one of the most commonly prescribed PIP medications by both set of criteria. Further analysis revealed that older adults from rural background (Odds Ratio (OR) 2.60, 95% Confidence Interval (CI) 1.20-5.65; P=0.015), TCA (OR 0.30, 95% CI 0.12- 0.75; P= 0.010), LABZD (OR 33.72, 95% CI 11.27-100.85; P=<0.001), atypical antipsychotics (OR 22.35, 95% CI 5.31- 93.99; P= <0.001) use were most common predictors for PIP medication prescribing. Conclusion: The use of PIP medication is highly prevalent among older adults according to Beers criteria and STOPP criteria. The study reflects a more comprehensive and sturdy nature of Beer criteria as it significantly detects more PIP medication than STOPP criteria.