The doctor may be in, but a lot of people aren't bothering to see her.
A new survey, commissioned by the medical scheduling company ZocDoc, found that 80 percent of Americans say they delay getting preventative health care, or forgo it. Millennials are even less likely to visit to the doctor, with 93 percent of them not scheduling them.
The survey findings come despite the fact that under the Affordable Care Act, a slew of preventive health services, such as blood pressure and cholesterol screening, vaccinations and "well-women" visits, must be covered by a patient's insurance plan with no co-payment or co-insurance charge.
Read MoreAthena Health CEO: No to health-care M&A
The ZocDoc survey identified work responsibility as the top reason for why people end up canceling or rescheduling their checkups, with almost half of the 2,183 respondents nationwide saying they canceled an appointment because of work. The survey had a margin of error of plus or minus 2.1 percentage points.
Even when people get sick and want to go to the doctor, they often don't schedule an appointment. Almost a third of the respondents said they didn't make appointments right away after getting sick because it's tough to actually get a visit scheduled with the doctor.
And 43 percent said it is easier to diagnose their own condition, often with the help of the Internet, and treat themselves. When people do try to book a visit over the phone, about 1 in 4 reported having difficulty reaching a person in the office.
Read MoreOregon dumps cold water on Obamacare rate requests
"They get dial tones and hold music," Dr. Oliver Kharraz, founder and president of ZocDoc, told CNBC on Tuesday.
To be sure, the survey's findings feed into the rationale for ZocDoc's business. But Kharraz told CNBC "the fact that our business exists ... shows how big the actual need is."