The main objective of this study is to determine the relative importance of farmer opinion leaders knowledge sources in cotton, wheat and maize crops, to identify the agricultural issues that were known by those leaders, to define the variables effect on leaders exposure degree to agricultural knowledge sources and recognize the hindrances that meet leaders to get agricultural knowledge. This research was conducted in six villages in Menoufia and Sohag governorates. The studied leaders in this research were chosen before, through previous study that was conducted by Agricultural Extension and Rural Development Research Institute for identification. The total number of studied leaders in this study was 205 as follows: 64 in cotton, 71 in wheat and 70 in maize. Data were collected by using questionnaire through personal interviews during 2003. Frequencies, percentage, weighted mean, simple correlation coefficient, variance analysis test were used to analyze data. The most important results could be summarized as follows: Agricultural extension agents, agricultural TV programs, farmer relatives, agricultural co—operative directors were important sources for leaders to get agricultural informations. The important agricultural knowledge obtained by leaders were as follows: In cotton crop: improved harvests, controlling for the greasy (black) cut worm, aphis, thrips, cotton leaf worm, americari, pink and sping boll-worm fertilization on right timing. In wheat crop: high yielding varieties, appropriate planting methods, planting by using grain drills, controlling weed and wild Oats. In maize crop: maize varieties, correct amounts of seeds for planting, irrigation on right timing, controlling plant diseases. It was found positive significant relation between the degree of simplifying agricultural ideas for farmers and degree of maize farmers opinion leaders exposure to knowledge sources. There are three important barriers met farmers opinion leaders in the three crops in getting agricultural knowledge through different sources as hindrances: agricultural magazines, lack of training for farmer opinion leaders on technical practices on the mentioned crops. Lack of audio visual aids, posters, samples, that help leaders to understand concerned practices.