The prediction of pressure drop in pneumatic conveying pipelines, for design purposes, can be approached by a number of techniques. However, it is generally accepted that the most reliable method is to base the predictions on data obtained from conveying trials in an instrumented test plant. Such trials are generally costly and so are usually limited to the minimum possible to obtain a reliable design. Thus, the ability to take data obtained under a particular set of conditions and use it to predict pressure drop under different plant conditions is important in keeping the cost of design trials to a minimum. One area in which such a technique is particularly important is in predicting pressure drop in vertical pipelines from data obtained in horizontal pipelines, since many plants contain sections of each, and the cost of conveying trials in both is often prohibitive. This paper will present pressure drop data obtained in both horizontal and vertical pipelines, allowing comparisons to be made. Simple models to relate horizontal and vertical data will be discussed and the general trends of available data presented.