Marketing margin is defined as the difference between the producer price and the consumer price and it can be affected by various factors. In this article, noting the fact that Sistan and Blouchistan province is one of the most important date producers in Iran, an attempt is made to estimate the economic function of factors affecting the date marketing margin in the province. The data required in this research has been collected through field survey and document analysis. The results of estimation of marketing margin functions obtained through utilizing a combination of models including the Price Increase Model, Relative Price and Marketing Margin. Data analysis indicates that farmgate price and harvest margin of dates are among the highly influential factors on the entire marketing margin. The retail-margin function is influenced by retail price and retailer cost and the wholesale margin function is affected by wholesale price and wholesaler cost. Calculation of market transparency determination criteria shows that due to the fact that the total of farm-gate price and marketing costs are less than the retail sale, there is lack of transparency in studied marketing channels, which in turn resulted in the declining market efficiency.