In this article 55 unpublished letters of Dr. Muhammad Hamidullah, addressed to his close relatives, are being produced. These letters shed new light on the life and scholarly activities of Dr. Muhammad Hamidullah. While in Paris, he remained in touch with his relatives in the Hyderabad-Deccan and Madras. These letters reflect that Dr. Muhammad Hamidullah acted as a religious and spiritual guide as well as a mentor and a ‘muftī’ for his relatives. He showed keen interest in their educational and religious activities and proved to be a source of encouragement and guidance for them. These letters are also a significant source on the scholarly contribution of his ancestors, especially their role in the dissemination of the teaching of Islam in South India. We also gain a sense of Dr. Muhammad Hamidullah's position on questions of juristic nature, where his orthodox views become evident.