Gas chromatography has generally not lived up to its potential for quantitative accuracy. This paper is the first report of a series of investigations in this laboratory directed toward learning more about the technique and hardware requirements for improving accuracy and precision. Some errors are chemical in nature. For example, some compounds, such as cholesterol, are prone to be lost in varying amounts on the column. Trimethyl Silyl Ether (TMS) derivatives will frequently decompose by hydrolysis upon standing. Hardware factors such as temperature dependence of flow controllers may contribute to appreciable errors. Sample fractionation, both prior to and during injection, may also be responsible for inaccuracies. The precision attainable, at the 95% confidence level, for an isothermal analysis of a seven component mixture is ±0.5% relative or better with Indium tube sample injection, or ±1% relative or better with syringe injection.