"Free" health care is health care that is provided by a national government to its citizens without charging users for specific services. Sometimes referred to as universal health care, this form of health care exists in a number of countries, including Cuba and Venezuela. The system has some advantages, but also a number of disadvantages.
"Free" health care is not, in fact, free--it only appears that way in the short term. Although the people receiving the medical services do not pay for treatment at the time at which they receive it, they do pay for the services in the form of additional taxes. Even if the country has a number of natural resources upon which to draw, such as Venezuela, which allows the government to fund such a health care system without raising taxes, it is still diverting money away from other uses or from distributing the proceeds to the country's residents.
When a person is insulated from risk, he may be more likely to engage in risky behavior. This concept is known as "moral hazard." In regards to health care, if a person knows that he will not have to pay for his own medical treatment, he may be more likely to commit acts that have a greater probability of resulting in injury. This leads to lower productivity, as well as a greater strain placed on the country's health care resources.
When people are forced to pay for their medical treatments, even a small amount, they are more likely to be judicious in the treatments they receive. If faced with the prospect of paying for them, the patient may choose to decline treatments that are unnecessary or have little likelihood of working. However, if the patient is not directly paying for his treatment, these shackles are removed. Under a "free" health care system, the patient may feel more of an incentive to receive as many treatments as possible, no matter how relatively ineffective, because he's not footing the bill.
In order to prevent the cost of the country's health care from spiraling out of control, many countries are forced to ration care. This means that instead of providing unlimited services to people, the government only provides certain medical services. This rationing of care can mean that people wait longer for fewer treatments. In the absence of a thriving private health care system, patients in need of treatment may have few places to turn to as alternatives.