Abstract: A socio-agronomical survey and a laboratory experiment on weed seed mixture with rice seed were carried out at the three different villages of Mymensingh district and in the laboratory of Bangladesh Agricultural University, Mymensingh respectively during the period from January to June 2002 to know the farmer’s knowledge and idea about the impact of weed seed mixture on the quality of rice seeds, and to know the status of seed purity in rice collected from different locations of Bangladesh. In the socio-agronomical survey, 100 farmers from six villages e.g. Kazirshimla, Dewanibari, Seedstore, Bharadoba, Churkhai and Rampur under three Upazilas namely Trishal, Bhaluka and Sadar were randomly selected for interview. Pre-prepared questionnaire were used to ask questions on different aspects of weed contamination with rice seeds. Results revealed that 90% farmers of the area cultivated IR50 and only 3% farmers grew BR2 rice variety. They got higher average yields from IR50 (1.96 t ha-1) than other varieties e.g. BR2 (1.65 t ha-1) and BR3 (1.75 t ha-1). Farmers found five noxious weed seeds e.g. Echinochloa crusglli, E. colonum, Cyperus iria, Scirpus spp. and C. difformis in the rice seeds. E. crusgalli was appeared as the notorious weed to rice farmers. Forty percent of the interviewed farmers were educated up to class five and literate farmers used higher seed rate, which led to less weed infestation in the field. Eighty nine percent farmers used their own seed, which were produced and processed with care, and there was less possibility of weed seed contamination. Eight percent farmers used seeds from market, which contained more weed seeds in rice seeds. Laboratory analysis of seed samples collected from different locations of the country revealed that location has an impact on the weed seed mixture in rice seeds. Samples collected from the village more away from Bangladesh Agricultural University, Mymensingh contained more weed seeds. The purity percentage of farmers saved seed was about 95% and it contained 0.08% weed seed. The weed seeds found in the farmers saved seed samples were E. crusgalli, E.colonum, Scirpus spp. and Cyperus difformis.