A THESIS SUBMITTED IN FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY OF SOKOINE UNIVERSITY OF AGRICULTURE. MOROGORO, TANZANIA.Information is one of the most valuable resources and potential ingredient for the advancement of agriculture. The introduction of mobile phones is believed to have the possible to supply the required information to the rural community. Ethiopia, like many other developing countries is adopting the use of mobile phones in many sectors including the agricultural sector. The overall objective of this study was to determine the potential of mobile phone usage in agricultural extension. The specific objectives addressed were to: (i) Establish the agricultural information needs and information seeking behaviour of farmers; (ii) Determine the extent of usage of mobile phones for accessing agricultural information by farmers; (iii) Measure the extent of interaction between mobile phone and radio in accessing agricultural information; and (iv) Examinefactors constraining the use of mobile phones in agricultural extension. To that effect, a cross-sectional survey research design was employed. The study population included all household heads who owned mobile phones in eightrandomly sampled villages. Multi-stage sampling procedure was employed to select 320 respondents. The quantitative data collected were statistically analysed to compute descriptive statistics, correlations and chi-square test. Multiple Linear Regression was used to examinefactors constraining the use of mobile phones. The results indicate the important types of agricultural information that farmers need and how frequently they seek them. 90.6% farmers made phone calls and over four-fifth (85.9%) of farmers received calls related to agriculture. Eight factors constrained the agricultural use of the mobile phone. These were age, level of education, distance to the nearest town, mobile phone ownership time frame and amount of money spent on mobile phone. Yet the others were information need and seeking behaviour, annual average income and mobile phone having FM handset radio.The study concludesthat, the information needs of farmers vary from farmer to farmer due to various factors. In the absence of any organized mobile-based extension service delivery, nearly all (97.2%) of the farmers used mobile phones for agricultural purposes, while more than half (57.8%) listened to FM radio on their mobile phones. The study also observedthe poor existence of interaction between mobile phones and FM handset radio.It is therefore recommended that regional bureau of agriculture should consider the information need of farmers and should develop mobile-based agricultural information dissemination system to enhance the information delivery to farmers and as wellplan the efficient use of FM handset radio.