Facing fierce competition from rival Walgreen Co., Longs Drugs plans to open four new stores in the next six months, marking its largest expansion in more than a decade.

The longtime isle retailer, an institution in Hawaii for more than 50 years, will open its first full-size drive-through pharmacy this month at the Pearl City Gateway. Next month it will open a store at the former Haleiwa Super Market on Oahu’s North Shore.

Longs, a wholly owned subsidiary of CVS Caremark Corp., plans to open a store in Ewa Beach on Fort Weaver Road in January and another this fall in Pahoa on the Big Island.

Walgreen has as many as nine island projects in the works.

CVS and Walgreen have been battling each other throughout the U.S. and brought their competition to Hawaii in the last three years.

"We really didn’t have a lot of growth for our larger stores for quite some time," said Robert Ingersoll, Longs vice president and general manager. "As new areas develop we’re always interested in making sure we can service those communities. There wasn’t a push (to open around the same time); it’s just how the pieces of properties came together."

In addition to the four new stores planned for the next six months, Longs has purchased 1.9 acres in Mililani Mauka to build a second drive-through pharmacy opening in 2012. The company also expects to relocate its Moiliili store in 2011 to the former Star Markets site. Longs officials added that more new stores are in the works for 2011, but they declined to disclose the locations.

The company’s last major expansion was in 1995 when it took over five Thrifty PayLess Inc. sites — including Moiliili, Salt Lake, Waianae, Kaneohe (at the Windward City Shopping Center) and Kapaa on Kauai. It added a store in 1999 in Ewa Beach and opened its most recent location in 2009 in Pukalani, Maui.

"It’s really about just finding the right real estate locations that are going to be convenient and accessible to our customers," said Michael DeAngelis, spokesman for CVS/pharmacy. "As the population continues to age, it fuels the demand for pharmacy services."

CVS Caremark Corp. of Rhode Island acquired California-based Longs in October 2008 for $2.9 billion. CVS changed the name of all Longs stores on the mainland to CVS but left the name Longs in Hawaii because of brand loyalty here.

Hawaii residents have long regarded Longs as a kamaaina institution, with loyal followers religiously searching its Sunday ads for savings on basic goods and services.

In the years prior to the CVS buyout, Longs had been focused on acquiring smaller pharmacies. In 2006 the chain bought and expanded Gulick Pharmacy, a small neighborhood pharmacy in Kalihi, as part of its new strategy.

Walgreen, the largest U.S. drugstore chain based on locations, entered the Hawaii market with its first store in November 2007, igniting a commercial rivalry with Longs. Walgreen has 7,800 stores nationwide, including about a dozen in Hawaii.

CVS, the No. 2 chain, owns and operates more than 7,000 stores nationwide, including 33 Longs Drugs stores and 13 Longs Pharmacies in Hawaii.

"Because time has become so fleeting for most people, it’s all about convenience, so people are going back to their neighborhood drugstore for their everyday needs," said retail analyst Stephany Sofos. "The convenience of buying a six-pack of beer or getting aspirin at the corner drugstore will always be a great need for people."

With new residential developments sprouting throughout the state, more neighborhood drugstores will benefit consumers, said Kapolei resident Claudia Quintanilla, 49.

"They’ve established themselves in the many years on Oahu and in our Hawaiian Islands," Quintanilla said. "Longs Drugs is part of our culture. Its popularity has been with our islanders for generations."