Eastman Kodak Co. yesterday posted its first quarterly loss in at least 55 years, the result of a huge loss from its forced withdrawal from the instant-photography business.

Kodak said it took a special pre-tax charge of $551 million in the fourth quarter, including $494 million associated with pulling out from instant photography.

The big charge resulted in a net quarterly loss of $194 million for the world's largest photography company, compared with net earnings of $204 million (87 cents a share) in the year-earlier period.

Kodak spokesman Charles Smith said the quarterly loss was the only one since at least 1930. He said financial records of the company's first 50 years after its founding in 1880 were not readily available.

Kodak stopped making and selling instant cameras and film in January after a federal appeals court refused to stay a permanent injunction won by Polaroid Corp. Polaroid said Kodak was infringing on its patents.

Other factors in the special charge were costs from the closing of facilities in Vincennes, France, and some facilities of its Verbatim Corp. subsidiary in the United States.

Kodak said its net sales in the quarter were $2.82 billion, up from $2.75 billion a year earlier.

For all of 1985, Kodak said its net income was $332 million ($1.46), down 64 percent from $923 million ($3.80) in 1984. The full-year results were hurt by special charges totaling $563 million, including the big fourth-quarter charge.

Its 1985 sales of $10.63 billion were essentially level with 1984's $10.60 billion.

*R. J. Reynolds Industries Inc. has reported increased fourth-quarter and annual net income from continuing operations for 1985, although profits were lower than a year earlier when discontinued operations were included in 1984 figures.

The tobacco and food industry conglomerate, which is based in Winston-Salem, N.C., reported fourth-quarter net income of $334 million ($1.17 a share), compared with $525 million ($1.85) in the same period of 1984.

Reynolds, which sold its service systems unit early in 1985, noted that when discontinued operations were excluded, its net income for the fourth quarter of 1984 was $259 million (89 cents).

Sales for the quarter ended Dec. 31 totaled $5.52 billion, compared with $3.53 billion a year earlier.

For the year, Reynolds reported net income of $1 billion ($3.60), compared with $1.21 billion ($4.11) in 1984.

Earnings for 1984 were $843 million ($2.80), without including discontinued operations.

Sales for the year totaled $16.6 billion, compared with $12.9 billion a year ealier.

*Republic Airlines yesterday reported record 1985 earnings of $177 million on operating revenue of $1.73 billion.

The net earnings -- equal to $4.74 per share -- represented a six-fold improvement in financial results over 1984, when Republic earned $29.5 million (76 cents a share) on operating revenue of $1.55 billion.

Republic President Stephen Wolf credited effective route realignment, careful cost control and employe support for the record year.

"Our financial performance and growing traffic strength made Republic an attractive merger candidate to NWA Inc., parent of Northwest Airlines," Wolf said.

Northwest has bid to purchase Republic for $884 million ($17 a share).

Republic earned $13.2 million in the fourth quarter of 1985, compared with a $10 million loss during the same period in 1984.

*Wendy's International Inc. yesterday reported record fourth-quarter and annual profits for 1985.

The restaurant chain, based in Dublin, Ohio, announced it had net income of $18.6 million (25 cents a share) during the quarter ended Dec. 31, compared with $17.7 million (24 cents) in the same period a year earlier.

Systemwide sales totaled $681.1 million during the quarter, a 9 percent increase from $626.7 million a year earlier.

For the year, Wendy's posted net income of $76.2 million ($1.03), compared with $68.7 million (93 cents) during 1984.

Systemwide sales for the year totaled $2.69 billion, compared with $2.42 billion during 1984.