HMOs often provide integrated care and focus on prevention and wellness. With HMO plans you must choose an in-network primary care physician (PCP), and then all of your care will be coordinated through that PCP to other in-network providers. So, if you need a specialist, such as a cardiologist (heart doctor), you’ll need a referral from your PCP first. Though, some HMO’s do not require a referral to see a specialist. HMOs do NOT cover any out-of-network healthcare costs, except in an emergency.