A project was initiated in Tanzania in the 2004 crop season to breed maize for high-yielding open-pollinated varieties (OPVs) and hybrid varieties with resistance to gray leaf spot (Cercospora zeae-maydis) and northern leaf blight (Exserohilum turcicum) and other major diseases like maize streak virus (MSV) and rust (Puccinia sorghi). These diseases cause significant yield losses ranging from 10 to 60% of the total maize produced in the country. There is no known resistance to gray leaf spot (GLS) in the OPVs grown commercially in Tanzania. The project also intends to select for other attributes such as farmer-preferred grain colour, grain type, early maturity, plant aspect and wide adaptability. For the first year, three trials were conducted. These included a trial consisting of 30 OPVs and hybrids from the National Maize Research Program (NMRP) and the International Maize and Wheat Improvement Center (CIMMYT)–Nairobi. These were screened in two locations, Madiira and Arusha Seed Farm (ASF) in Arumeru District. Another trial included 90 inbred lines that were obtained from CIMMYT Nairobi and screened at ASF. A third trial involved 21 inbred lines from the International Institute for Tropical Agriculture (IITA), also screened at ASF. The trials were conducted under partial irrigation since the crop season was dry. They were arranged in an alpha-lattice design with three replications. The experimental area was surrounded by two rows of a susceptible variety, CG 4141, which served as a disease spreader. We artificially inoculated the test varieties and the spreader rows with GLS. There were significant differences among the varieties in most of the parameters assessed. For the 30 varieties that were obtained from NMRP and CIMMYT-Nairobi, grain yield ranged from 0.9 to 10.5 t ha–1. The highest-yielding OPV was TMV-1, which yielded 6.8 t ha–1, while the highest-yielding hybrid line was UH6304 with a yield of 10.5 t ha–1. Days to anthesis varied from 60 to 94 days at ASF and 57 to 105 days in Madiira. Six cultivars showed resistance to MSV at Madiira and two at ASF. Only one variety was resistant to MSV at both locations. Five varieties were rated resistant to northern leaf blight at Madiira. At ASF, three varieties showed resistance to the blight. These were also rated resistant at Madiira. Five varieties were rated resistant to leaf rust. At Madiira, rust did not develop enough to enable a clear distinction to be made between varieties in terms of resistance. Among the 90 lines that were obtained from CIMMYT-Nairobi, yield ranged from 0.1 to 2.8 t ha–1. This trial was begunlate and diseases did not develop fully. Anthesis of these cultivars ranged from 62.3 to 97.7 days. Twenty-three lines performed best for the other parameters. In the third trial, grain yield ranged from 0.1 to 2.9 t ha–1. Anthesis ranged from 79 to 114 days. Diseases did not develop much in this trial due to low humidity. Overall, GLS developed very little on the inoculated plants at both sites due to low humidity. Improvement on GLS inoculations will be made. The best lines will be used in a crossing block next season. Received for testing in the northern zone next season and in southern Tanzania, where planting starts in December, are 111 OPVs, inbreds from CIMMYT-Harare and 50 landraces.