The study was conducted in Sumbawanga Rural District in Rukwa region. Its objective was to examine the influence of grain quality and standards in maize trading. Specifically, to find the significance of maize cleaning, grading and standardizing in grain marketing, to examine the significance of the road condition in determining maize buyers’ accessibility to buying posts and the significance of the number of maize buyers in fluctuating farmers’ maize selling price. Purposive multistage sampling technique was employed to get 180 respondents; 60 traders and 120 producers. A questionnaire and a checklist of questions were used to collect qualitative and quantitative data. Linear and logistic regression models were used to test the hypotheses and inferences were made at 5% level of significance. Maize cleaning reduced net marketing margin at a rate of 0.031; with p = 0 . 710 it was thus found to be statistically insignificant. Grading of maize into classes was also statistically insignificant ( p = 0 . 094 ). However, it had a positive influence at a rate of 0.136 on the trader’s net marketing margin. Standardizing of maize had no statistical significance on net marketing margin ( p = 0 . 693 ) although it had a positive effect on the net marketing margin at the rate of 0.033. Cleaning, grading and standardization of maize increased marketing costs and leaving them uncovered in the net marketing margins.