Lattice design for testing hybrid corn is being used since 1939 at the Genetics Department of the Instituto Agronômico de Campinas. Preliminary observation from the comparative analysis of experiments carried out in 1950 and 1951 as lattice and randomized blocks indicated that only a small increase in efficiency was obtained by use of lattice analysis. Presented here are the results of a larger number of comparisons of both types of analysis for 32 lattice experiments carried out at the Central Station of Campinas, 12 from Ribeirão Preto Station and 7 from Pindorama Station of this Institute. Both the efficiency of the lattice design and the precision of the experiments were calculated and the results are presented in table 1. The results of these experiments analysed as a lattice in comparison with randomized blocks gave an average efficiency increase of only 8.2% for the experiments from Campinas, 9.6% for R. Preto and 1.7% for the Pindorama experiments. The average coefficient of variability indicated that the experiments from Campinas and Pindorama, were more precise than that from It. Preto where the stand of plants in the field was usually lower due to insect attack. It was concluded that the small increase in efficiency of the analysis as lattice in comparison with randomized blocks must be due to the small size of the plots and location of the replication in the field.