Background: Evaluation of prescription patterns would determine the drug utilization with main emphasis on rational use of medicine. The problem of irrational use of drugs is rampant particularly in developing nations. The present study was undertaken for evaluating the prevailed prescription patterns in tertiary hospitals with diarrhoea and/or Acute Respiratory Infection (ARI) to address specific areas of deficiencies and deviation from the available guidelines. Method: We conducted this observational cross-sectional study from August 2019 to December 2020 in Medicine & Paediatrics outpatient departments and Urban Health Training Centre in two Government teaching hospitals in West Bengal, India. We included 630 prescriptions (511 – ARI, 119- diarrhoea) and evaluated in terms of disease and medicine prescribed including antibiotic related indicators. We compared prescription patterns across different age groups, different strata of prescribers and compared against WHO standards. A Rational Use of Medicine Consensus (RUMC) committee was formed and the prescriptions were assessed for appropriateness independently by a pharmacologist and clinician. Deviations, if any, were ascertained from the available guidelines and the acceptability of the deviations were determined by consensusResult: Age and sex were mentioned in all prescriptions however signs & symptoms, provisional diagnosis and follow up visit were mentioned in 90.3%, 4.9% and 67.9% prescriptions respectively. Body weight was mentioned in 88.5% of prescription of children (< 18 years). Higher rates of Fixed Dose Combination (51%), lower proportion of generic drug (23.3%) and adherence to hospital formulatory (36.5%) were some the major concerns identified. Antibiotics prescription rate (APR) and multiple antibiotic prescription rate (MPR) were respectively 57% and 10%; both found significantly higher for diarrhoea than ARI. Deviations from Standard Treatment Guidelines were found in 98.9% prescriptions and 90.4% of which were unacceptable. Agreement between clinician and pharmacologist was observed in 90% prescriptions (Kappa -0.114). Deviations were most commonly observed with prescriptions by interns and house-staff (99.6%), whereas acceptable deviations were more frequent among the residents (15%).Conclusion: We conclude that in light of identified irrational prescription patterns, development of level specific treatment protocol coupled with periodic training of physician including junior doctors is required to ensure rational medicine practice.