While Tanzania has been facing food shortage for some decades, little efforts have been made to elicit optimal crop yields. To limit this problem, there is a need for a robust agricultural policy that aims at stabilizing agricultural production and socio-economic entitlement among the farmers. The present study analyses the production trend of maize, sorghum and millet (i.e., staple food crops) under rain fed agriculture in Kongwa District, the semi-arid agro-ecological zone of Central Tanzania, and envisage their implications to food security and policy. We collected a set of crop data (1980-2015) from the Ministry of Agriculture, Livestock and Fisheries. In addition, 400 respondents were sampled randomly in the study area during household survey while a series of interviews and discussions were conducted mostly basing on the expertise. The Mann-Kendall Test and Microsoft excel (window 13) and theme content methods were employed for data analyses. The results showed that the production trends for maize, sorghum and millet yields have been decreasing at R2 = 0.40, 0.35 and 0.11 respectively and this trend was supported by 80% of the respondents. This decrease was greatly influenced by the temporal decrease in the mean annual rainfall (R2 = 0.21). The diminishing production trend has already decreased food security for 30% in the area. Since agricultural policy can be among the main sources of this poor yields, an explicit and sound agricultural policy should be the central aspect in planning and implementing agricultural activities.