Travellers tend to worry about contracting infectious diseases when in the tropics, but infections are a rare cause of serious illness or death in travellers. Pre-existing medical conditions such as heart disease, and accidental injury (especially traffic accidents), account for most life-threatening problems. Becoming ill in some way, however, is a relatively common thing. Fortunately, most common illnesses can either be prevented with some common-sense behaviour or be treated easily with a well-stocked traveller’s medical kit.
Health issues and the quality of medical facilities vary enormously depending on where and how you travel in Vietnam. Many of the major cities are now very well developed, although travel to rural areas can expose you to a variety of health risks and inadequate medical care.
Some international hospitals/clinics in Hanoi and Ho Chi Minh City (American, French and German doctors on staff)

In Hanoi: (tel code: 84-4)
Hanoi French Hospital
1 Phuong Mai Str.
Tel: 577-1100, emergency: 574-1111

Family Medical Practice
Unit 109-112, Van Phuc, Blog A1, Kim Ma Str.
Tel: 843-0748 (24hours))

International SOS
31 Hai Ba Trung Str.
Tel: 934-0666, emergency: 934-0555

In Ho Chi Minh City: (tel code: 84-8)
Vietnam-Korea Friendship Hospital
12 Chu Van An Str.
Tel: 843-7231

International SOS
65, Nguyen Du Str.
Tel: 829-8520, emergency: 829-8424

Saigon International Clinic
8 Alexandre de Rhodes Str., District 1
Tel: 823-8888

Gia Dinh International Hospital
1 Trang Long Str., Bin Thanh District
Tel: 803-0678

Franco Vietnamese Hospital
6 Nguyen Luong Bang Str., District 7
Tel: 411-3333

Resources of Health Advice for Travellers
Read the General considerations about International Travel & Health, including these issues:
Travel-related risks
Medical consultation before travel
Medical kit and toilet items
Travellers with pre-existing medical conditions and special needs
Insurance for travellers
Role of travel industry professionals
Responsibility of the traveller
Medical examination after travel
(Source: World Health Organization (WHO)