Five three point tests are reported for chromosome 1 and four three point tests for chromosome 3. The tests were analysed in the F3 generation. Maps for two regions on chromosome 1 comprising five and four genes respectively, can be constructed from the data obtained. The map spanning the distancecer-f toert-m confirms previous results for this interval. As observed earlier, coefficients of coincidence larger than 1 corresponding to negative interference are found in this region of chromosome 1. It is suggested that the consistent occurrence of negative interference in this interval is due to its location close to the centromere. In the other region studied on chromosome 1 normal positive interference is observed. On chromosome 3 a linkage map of the four markers analysed is presented. Positive interference is found in the three point tests of this region.