A cross-sectional, descriptive study was conducted at the Holy Family Red Crescent Medical College (HFRCMC) in Dhaka, Zahurul Islam Medical College (ZIMC) in Kishorgonj and Jalalabad Ragib Rabeya Medical College (JRRMC) in Sylhet. The study was done to evaluate the practitioner’s knowledge about rational prescribing and use of different sources of drug information using INRUD indicators and WHO guideline by Drug and Therapeutics Committee. Data on the use of different sources of information were collected by structured questionnaire. Ninety (90) general practitioners from HFRCMC, 76 from ZIMC and 68 from JRRMC were interviewed in the study. It was found that prescribing rationality is a physician characteristic. Younger General Practitioners prescribe in a more rational way than their older colleagues and this is partly reflected in the patterns of obtaining information. None of the studied professional sources of information seemed to have a great impact on prescribing rationality, with the exception of reliance on general medical journals instead of on drug oriented journals as a source of drug-information. This was negatively associated with prescribing rationality as well as reliance on the information of pharmaceutical companies.