Dr Frederic Mohs, a general surgeon, developed the Mohs Technique. This abstract aims to describe the history of Mohs surgery. When Dr Mohs was a research assistant, he injected various chemicals into rat tumour tissues to assess the reactions. He discovered that injecting 20% zinc chloride solution to rat tumour and normal tissue caused tissue necrosis which had well-preserved histology for both the tumour and normal cells. He was able to prepare frozen sections using this tissue for microscopic analysis. This finding formed the basis of this technique, and he coined the term chemosurgery. In 1936, Dr Mohs started performing chemosurgery on humans. He applied a zinc chloride paste to the cancerous area to fix the tissue. This was left to penetrate for at least a few hours. He would then excise the tissue, prepare the specimen into frozen sections and assess it under the microscope. This technique allowed him to identify specific areas of involved margins and re-excise the corresponding area only. This would be repeated until there were no more cancer cells found. Reconstruction would be performed in a delayed fashion five to seven days after the resection. In 1953, Dr Mohs used a fresh-tissue technique on an eyelid carcinoma to avoid applying the irritating zinc chloride paste near the eye. This technique involved thin excisions which was then sectioned and prepared ex-vivo. The benefits of this technique compared to the original method are that it avoids use of the irritating zinc chloride paste and allows excision and reconstruction to be performed on the one day. Now Mohs surgery has become a widely used technique amongst dermatologists. Many believe it is the most precise and accurate method of skin cancer excision with cure rates of around 99%.