The Isa Upanishad is so called because it starts with the word Isa. Isa means the Lord who is the inmost Self of all. Unlike other Upanishads the Isa is all in verse and many people think it is the oldest and best of the Upanishads. It is found in the Sukla Yajur Veda. The nature of Brahman or Paramatman and our relationship with it is the subject of enquiry of this Upanishad. It proclaims the divinity of man and nature and the spiritual oneness of all existence. It asserts that God is enveloping everything nay more God is in everything. It can be said that this Upanishad provides the fundamental theme of Vedantic thought. This volume is a simple translation of the Upanishad with explanation and includes an introduction. It follows Shankaras interpretation. This compilation is based on Swami Lokeswaranandas weekly discourses on the Upanishad.