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Witchweed;(Striga asiatica (L.) Kuntze, has been identified by Tanzanian farmers as one of the major biotic constraints to Maize and Sorghum production in semi and subtropical regions of the country. The most affected population group is the resource-poor farmers who cannot afford to purchase agricultural inputs such as fertilizer. Average yield losses of 40–90% caused by Striga are common on farmers’ fields in Striga-prone areas. On-farm trials were conducted for two seasons, 1997 and 1998 in Maramba division in Eastern Tanzania to verify on-station results on the control of Striga by intercropping of maize with cowpea. Ten farmers were selected to carry out the trial under the criterion that their fields were naturally infested by Striga. Plot size was 10m x 10m. Striga plants were recorded from the net plot of 6m x 5m at 9 and 12 weeks after planting and grain yield of maize was determined at harvest. Lowest Striga numbers were observed from treatments where maize was planted in the same hill with cowpea followed by in alternate hills. Contrary to the Striga numbers, highest maize yields were obtained from the sole maize treatment, but the results were not statistically significant. The relatively low number of Striga plants in the intercrop indicated a reduced potential for flowering, capsule production and consequently, a reduced capacity of increasing the Striga seed bank in the soil. From farmers’ evaluation, they preferred intercrop in the same hill because it reduced Striga numbers and they were able to harvest two crops from the same field.