Seeds of seven varieties of cotton produced at different regions of the States of São Paulo and Paraná (Brazil) were submitted to germination tests at two laboratories: Instituto Agronômico de Campinas (IAC) at 20 - 30°C and Divisão de Sementes e Mudas (DSM) at 30°C. The substrata used for the tests were cotton towels desinfected differently at each laboratory. The statistical analysis for numbers of normal and abnormal plants (infected) showed significant differences between regions, varieties, laboratories and substrata. Several significant interactions including these variables were also detected.