Striga spp., commonly known as witchweed, is a major pest on maize in Kenya and results in extensive crop losses for farmers. More than 46,000 hectares in western Kenya are infested with Striga, causing an equivalent yield loss of USD 10 million annually. A collection of germplasm with putative resistance to Striga hermonthica was acquired from pre-existing breeding projects in Kenya and the International Maize and Wheat Improvement Center (CIMMYT)-Mexico. Germplasm from Kenya was 30 collections of teosinte background, 10 populations from Kakamega previously identified to have tolerance to Striga, 3 local broad-based breeding populations from the Kenya Agricultural Research Institute station at Muguga and 1 check. Germplasm from Mexico was in two categories: a population of 72 lines that contained transposable elements induced mutations, and seven wild relatives of maize belonging to Zea perenis, Z. parviglummis, Z. luxurians and Z. mexicana. The 44 collections from Kenya were planted at Alupe (Kenya) in the 2002 long rain season for selection and generation advance under artificial inoculation with Striga hermonthica. In each population selections within and between rows were done to identify those lines and plants with a Striga score of < 0.5, above-ground Striga emerged plants < 2, and < 4 Striga plants attached on the roots. Final selection of Striga-resistant lines was done at the S4 generation. Results indicated the 35 S4 lines rated best for Striga were selections from populations with teosinte-derived materials: 56//602, and 44-6. The next best population for Striga resistance was Early-N-Pop and MGA. The 35 lines are being used to form Striga-resistant synthetics. In a separate trial, evaluation of 72 lines with transposable induced mutations identified 21 lines as resistant to Striga. Selected lines had above-ground Striga emergence of < 2 and below-ground Striga attachments on roots of zero. This was evidence that there is genetic Striga resistance in the mutator lines. The various lines also showed differences in the stem-to-root ratio under Striga infestation, indicating the potential of different lines to have higher yields in Striga-infested areas. Most lines had a stem-to-root ratio of > 4.5, which is above that of the check (H513). The line JI10-5 had a stem-to-root ratio of 5.5; JI10-14 had an even higher ratio of 7.9. Striga sources thus identified need to be incorporated into adapted materials for variety improvement.