The main focus of the study was to identify the indigenous knowledge system being used by the rural men in farming and household activities and also to examine its extent. Data were collected from Poba upazila under Rajshahi district and Gabtoli upazila under Bogra district in Bangladesh from 125 randomly selected rural men out of total population of 1,145 from 15 February to 14 May, 2009. The fifty potential indigenous knowledge systems were identified through participatory rural appraisal prior to finalizing the schedule. The findings reveal that greater proportion of rural men were illiterate, middle aged categories, small farmer category, medium agricultural and environmental knowledge category, high level farming experience, medium cosmopoliteness, medium communication exposure, no organizational participation and moderately favorable category. Among the 50 identified indigenous knowledge systems, “Setting up bamboo sticks, branches of trees etc., in rice fields to let the birds sit and eat away insects” reachedthe highest extent of use by the farmers in agricultural practices. “Soaking boro rice seeds in water for 1-3 days before sowing in the bed for rapid germination”, “Drying mature bottle gourds (Lagenaria vulgaris) in the sun and storing the seeds inside without rupturing the fruits” and “Keeping rice seedlings under shed for 1-2 days before transplanting for the purpose of increasing tolerance” tookthe 2^nd, 3^rd and 4^th position regardingthe extent of use. Considering farmers’ practicing category, the highest proportion (47.2%) of the respondents belonged to the low user as compared to 39.2% in the moderate user and 13.6% in the high user. Recommendations were forwarded to the extension specialists, researchers and administrators to undertake desk and experimental research concerning indigenous knowledge systems.