This study was conducted to investigate ‘Seasonal diversity and abundance of insect-leafhoppers in Bt and non-Bt cotton fields of Nalgonda district of Telangana state, India.’ Sweep net and hand-picking method was used for the collection of insect-leafhoppers. we observed two species of insect-leafhoppers in Bt cotton and four species insect-leafhoppers in non-Bt cotton fields during 2018-2019 cotton season and three species insect-leafhoppers in Bt cotton and five species insect-leafhoppers in non-Bt cotton fields during 2019-2020 cotton season. We did not find insect-leafhoppers in July, 1-species of insect-leafhoppers in August, 1- species in September, 1-species in October, 2-species in November, 1-species in December and 1-species in January on Bt cotton and we did not find insect-leafhoppers in July, 1-species in August, 1- species in September, 1-species in October, 3-species in November, 2-species in December and 1-species in January on non-Bt cotton fields during 2018-2019 cotton cropping season and We did not find insect-leafhoppers in July, 1-species in August, 1- species in September, 3-species in October, 3-species in November, 3-species in December and 1-species in January on Bt cotton and We did not find insect-leafhoppers in July, 1-species in August, 1- species in September, 5-species in October, 5-species in November, 3-species in December and 1-species in January on non-Bt cotton fields during 2019-2020 cotton cropping season. Seasonal diversity and abundance of insect-leafhoppers showed lower differences between Bt and non-Bt cotton fields. Ecological indexes were calculated.