It is well known that trachoma is an infectious chronic infectious ocular surface disorder caused by the bacterium Chlamydia trachomatis, and one of the main blinding diseases, especially in Africa. An estimated 2.2 million persons are visually impaired due to trachoma, among which 1.2 million are blind [
1,
2]. Conjuctival inflammation is the main characteristic in primary infection of trachoma. As a result of repeated infection, trichiasis and corneal scar may present at late stage which can cause irreversible visual loss [
3]. Trachoma is more common in communities with underdeveloped economy, drought and poor sanitation [
4,
5]. Data from the Ministry of Health in China showed that the prevalence of trachoma ranged from 63.0%~ 98.0% in 1958 [
6]. In the first national survey of blindness and low vision in China, trachoma was the second cause of visual impairment [
7,
8]. Trachoma interventions were implemented in China for decades. Following the WHO recommendations to reach the target of WHA51.11 Global elimination of blinding trachoma [
9], a trachoma rapid assessment (TRA) was carried out in 14 provinces in P.R.China as a key activity to determine the current situation of trachoma and provide information for future planning. Yunnan province locates in the southwest border of China and is at the far eastern edge of the Himalayan uplift. Yunnan has an area of 394,100 km
2, 4.1% of the nation’s total, and shares a border of 4060 km with Myanmar, Laos and Vietnam. Mountain land accounts for almost 94% of its total area. The elevation ranges from 76.4 to 6740 m and the average annual rainfall ranges from 584 to 2300 mm. Because of diverse climate and poor traffic conditions, economic development level in Yunnan is relatively backward with more poverty-stricken counties. The prevalence of trachoma was as high as 63.1% in Yunnan Province in 1963 [
10]. In 1987, trachoma was reported as one of the three leading causes of blindness in the National survey of blindness in Yunnan. Among 109,181 participants, 107 people were blind caused by trachoma (0.098%) [
8]. In 1999, the government of China included Yunnan as one of 12 provinces in which trachoma was still believed to be present [
11]. In recent years, trachoma continued to be reported in school health reports [
12‐
14]. Severe drought in recent years led to a shortage of drinking water in 7.42 million people. In the majority of mountainous and the mid-altitude level districts across the province, it is common practice for the whole family to use the same basin of water for face washing. Yunnan Province has been assumed by the government as a region in which trachoma was a public health problem. However, a large scale prevalence survey has so far not been carried out in Yunnan Province and assumptions are commonly based on clinical reports only. As part of a number of TRAs conducted across the country, a TRA was also conducted in Yunnan Province. Purpose of the survey was to assess the presence of active disease, defined as trachomatous inflammation, follicular (TF) and/or trachomatous inflammation, intense (TI) among children aged from 6 to 8 and trachomatous trichiasis (TT) and/or trachoma-related corneal opacity (CO) among those aged 15 and over.