Here’s a familiar scenario: You have a sore throat or an earache. It could be just a virus, but you want to get it checked out to make sure. Good luck getting in to see your regular doctor right away.

Typically your best option is an urgent care clinic or the emergency room, where you could wait hours to be seen, in a room filled with other sick people. For Lisa Loscalzo, who spent the early part of her career in health care, this didn’t make sense. Especially when she saw highly qualified health care professionals–nurse practitioners–whose skills and expertise were being underutilized.

Loscalzo just needed a place to connect these professionals with patients seeking treatment for minor illnesses.

A supermarket may not seem like the obvious venue, but Loscalzo saw the benefits: open long hours, centrally located, pharmacy attached. Most importantly, it’s a place frequented by the primary health-care decision-makers in most families (women).

People told Loscalzo her idea for putting walk-in, nurse practitioner-led health clinics in supermarkets was crazy. “We did our best to not focus on all the negativity and the noise and stay focused on our vision,” she says.

Five years later, her company, the Little Clinic, operates 150 “little” clinics in Kroger and Publix stores in 10 states–and sparked lots of rivals.

In September, Fortune picked Loscalzo as one of 10 Most Powerful Women Entrepreneurs–a program recently launched in partnership with American Express (AXP). Lozcalzo has faced speed bumps, whether tackling regulatory obstacles or training nurse practitioners in customer service. But she believes the Little Clinic is a business with a higher calling as a solution for health-care reform: “We’re accessible. We’re affordable. We’re high quality.”

More from Loscalzo, who shares lessons learned as an entrepreneur.

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