After the Lao PDR changed from a central planing economy to a market economy, a large amount of money was needed to develop their country. Of many resources based industries, forestry and mining are the main industries concerned. Forestry provides income in the short run but leaves behinds a long term damage to the environment. Mining is another alternative for Lao government to gain income and inflow of capital. A number of Thai companies had signed contracts with the Lao government to develop mining in the Lao PDR.This thesis proposes to study the opportunity of Thai mining companies investing in the Lao PDR. The necessity of the Lao government's need to promote mining industry was confirmed. Information relating to mineral deposits in Laos were collected and analyzed. Coal was chosen for the study due to its significance to the economy of the Lao PDR. Supply of coal for use in Thailand was studies and demand of coal by Thai investors was confirmed. Three important coal deposits were chosen. An Economic model representing each deposit was made. Financial analysis for each deposit was made using normal financial evaluation tools. Other factors affecting the undertaking in Lao PDR were studied.