J. B. S. Haldane (1892-1964) was an outstanding scientist and a polymath who contributed significantly to physiology, genetics, biochemistry, statistics, biometry, cosmology, and philosophy, although he himself possessed no formal qualifications in any branch of science. His early science training was provided by his father, Oxford University physiologist J. S. Haldane, and the rest was self-taught. The author came to know him well as his student during his last years, which were spent in India (1957-1964). Haldane's unique intellectual qualities and the research undertaken by his associates in India during those years are described.