ObjectivesAs one of vulnerable groups in society during the transitional period, rural-to-urban migrant workers are usually compelled with lower social status, intense labor, longer labor hour, lower income, insufficient protection from social security agencies and poor labor protection. As a marginal group, their rights are not effectively protected. Most migrant workers may not receive basic medical services; their relatively low social-economic status determines that their health status is least optimistic. Purposes of this study are thus as follows:(1) To investigate demographic features of migrant workers during China's economic and structural reforming period and study their social-economic status.(2) To conduct quantitative survey on migrant workers' health status in virtue of Health Related Quality of Life (HRQOL) evaluation, and compare the outcome with other populations in China.(3) To compare index of HRQOL of migrant workers with different socio-demographic features so as to screen out major socio-demographic factors that influence migrant workers' health status.(4) To suggest policy reforms hi order to improve migrant workers' health status according to the findings in this study.Methods(1) Quota sampling is used. 3319 rural-to-urban migrant workers, having been working in Hangzhou City proper for no less than 3 months, were investigated. Questionnaires were distributed to dozens of construction sites, markets, shopping malls, manufacture factories, restaurants and households, and collected. The investigated were required to fill out the MOS 36-item Short Form Health Survey (the Chinese version of SF-36) and Nottingham Health Profile (the Chinese version of NHP), which involve information of their demographic features, occupation, income and living conditions.(2) Migrant workers' Health Related Quality of Life is evaluated by SF-36. When one half or fewer of the items in a scale were missing, the mean of the non-missing items was used to represent the scale. A scale score was declared missing when more than one half of the items were missing. We calculated the percentage of respondents having completed each item, the percentage of respondents having completed all theitems within each scale and the percentage of respondents for whom scale scores were computable. We also compared each scale score of SF 36 between groups of different socio-demographic features such as sex, age, education, income, labor hours and so on.(3) Migrant worker's Health Related Quality of Life is evaluated by NHP. We calculated the mean and median of six scales of NHP, and then compare them between different socio-demographic features such as sex, age, education, income, and labor hours.(4) The outcome of HRQOL measured by SF-36 and NHP were compared in this study. The method of canonical correlation analysis was used to study the relationship of SF-36 and NHP. We drew trend curves of scores registered in SF-36 and NHP, and conducted typical analysis of correlation, so as to evaluate the consistency of both forms in judging the same group.(5) Correlation analysis of migrant workers' socio-demographic features and health status was conducted. We calculated, from the outcomes of SF-36, migrant workers' scores in Physical Health and Mental Health, and Single Factor Analyses were conducted to find the correlation between PH / MH and varied socio-demographic features. Logistic Regression Analyses were conducted respectively in PH and MH to stydy the major factors affecting migrant workers' physical health and mental health as far as socio-demographic features are concerned.(6) Raw data derived from the questionnaire were input twice and checked automatically by epidemic statistical package EpiDATA 2.0 and then analyzed by SPSS11.0 for windows.Main Results(1) Socio-demographic features of rural-to-urban migrant workers: male workers occupy 67.9% while female occupy 32.1%; average age is 28.8 with a range from 73.2 to 13.1; sin