Trishal () is an upazila of Mymensingh District in the Mymensingh Division of Bangladesh. The Bengali poet Kazi Nazrul Islam attended a school here.
According to the 2022 Bangladeshi census, Trishal Upazila had 119,144 households and a population of 491,483. 10.87% of the population were under 5 years of age. Trishal had a literacy rate (age 7 and over) of 71.44%: 72.43% for males and 70.48% for females, and a sex ratio of 98.15 males for 100 females. 58,102 (11.82%) lived in urban areas.
Trishal Thana was formed in 1909 and it was turned into an upazila in 1983.
Trishal Upazila is divided into Trishal Municipality and 12 union parishads: Amirabari, Bailar, Baliparar, Dhanikhola, Harirampur, Kanihari, Kanthal, Mathbari, Mukshapur, Rampura, Sakhua, and Trishal. The union parishads are subdivided into 91 mauzas and 158 villages.
Trishal Municipality is subdivided into 9 wards and 12 mahallas.
Trishal is famously known for its deep connection with the National Poet Kazi Nazrul Islam, who spent a significant part of his childhood and early education here. Notable heritage sites include: