Interpretation of interwell tracer records from waterflooding oil reservoirs using spreadsheets. Neuquina Basin, Argentina This paper presents a methodology based on the use of conventional worksheets to analyze and interpret interwell tracer records from waterflooding oil reservoirs, evaluating injection flow characteristics and reservoir parameters such as: 1. Distribution of the injected flow and volumes contacted by the injection. 2. Streamlines for different injection patterns: five spot, inverted seven-spot, direct line drive. Evolution of the advancing front. 3. Anisotropy 4. Heterogeneity 5. Sweep evolution 6. Effective permeability in contacted volume The interpretation is based on a simulation, fully implemented on a spreadsheet. The methodology developed is a daily, accessible and easy tool for the interpretation of tracer records by the reservoir engineer. Finally an analysis of a real case is shown