TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe industry is focusing on cost reductions by saving on expensive rig time and on reducing the impact on the environment during well testing. Decisions regarding field development are increasingly taken based on the results of samples and data obtained by wireline formation tester/samplers (WFT/S) and not on data obtained by flow to surface during a drill stem test. The use of oil-based mud to increase the drilling rate is also becoming more common. These measures reduce the likelihood of obtaining quality fluid samples and increase the uncertainty in field development projects related to fluid data. A systematic approach to fluid sampling is presented which discusses the different aspects related to the quality of fluid data obtained depending on the sampling method, type of reservoir fluid system and formation properties. Recommendations for the decision making process are presented.