The knowledge of factors that have influence over the operational efficiency of the Brazilian ports may be of greatvalue to orientate the investment plans on the waterway transport system. To identify the most relevant variables of thissystem, it is proposed the simple correlation between four factors - vesselâs frequency, average consignment, loading/discharging rate and average waiting time - with the annual loaded / discharged tonnage of inputs that are significant tothe trade balance and the exports of Brazil - iron ore, petroleum coke, bauxite, soybean meal and bulk sugar. The statisticaldata used for this study was gathered by the National Agency for Waterway Transportation (ANTAQ) during 2008 and 2009.It was concluded that each product showed a different matrix of correlations and, what is significant, the analysis indicatedthat only the factor waiting time did not show correlation with any processed tonnage in 2008 and 2009. This conclusionbecomes relevant, because it shows the necessity of investment plans customized by input and informs that the variablewaiting time could be neglected in these plans under similar conditions as to the exposed scenarios of this paper.