This book contains almost everything related to subject of potency. In chapter-I, several related topics along with the various editions of Organon are discussed. In Chapter-II need for the LM potency, its preparation, its comparison with centesimal potency, its administration and in fact all related topics are ably discussed. Chapter -III gives the cases treated by LM Potency by well-known Dr Harimohan Choudhury, father of the Author and cases treated by himself using the LM potency. In short all topics related to the subject are discussed and full justice to the subject is done. It is a fact the Homoeopathy as has been practices by most homeopaths is based on the 4th edition of the Orgagnon [1828) and the first edition of the Chronic Diseases [1829] where single dry dose and then wait method is followed. This method was made more popular by Dr Kent. In 5th edition of the organon [1833] this dry dose method was changed by Hahnemann into a solution or liquid method and frequent repetitions was recommended and finally in 1843, in the 6th edition of the Organon the use of LM potency in liquid was recommended.