If you're planning to go to HK to get a Z visa, be wary. You require a health check done either in your own home country or in China. The invitation letter has to state where you are applying for your visa. If it is in your home country or at the embassy in Hong Kong. If you also plan to get health check in HK, DON'T. The consulate does not accept it, and if they do. You need to get it redone in China anyhow (double the xray dose). (You will have to redo it also if you do your initial health check in your home country). Americans or any other nationality except Canadians, can't get a 5 day pass (168rmb at the border when you take the subway) to go to Shenzhen, they have to get a full L visa just to get your health check. It takes 5 working days not including weekends. So if you go back to Hong Kong, you require to apply for another L visa to pick it up (stay in Shenzhen until you got the health check). Also note of caution, many americans and other nationalities have been turned away to their native country to apply for the z visa. They are getting stricter and there is talk that the visa runs in HK will be abolished in the future. If you can, start the process from your home country. Some get through some not. If you are willing to risk it ... use a visa company to do it for you.