PINE BLUFF, Ark. (AP) _ Character assassination is what Mayor Carolyn Robinson calls her city's ranking at the bottom of a 333-city list of U.S. metropolitan areas.

The upcoming edition of the ''Places Rated Almanac,'' which rates U.S. metropolitan areas of 50,000 or more, reportedly has Pine Bluff at the bottom, but the publisher declines to confirm the rating.

''It's sort of like blackmail or something, a violation of character,'' Mrs. Robinson said. ''It's like a character assassination of your city.''

When the last almanac appeared in 1985, Pine Bluff was second to last among 329 places. The new edition, to be published by Prentice Hall in New York, hits the sales racks Nov. 1.

The ratings are based on cost of living, climate, transportation, education, crime, jobs, arts, recreation and health, and the environment.

Mrs. Robinson and civic leaders publicly challenged the 1985 rankings, but time around, she said she won't defend Pine Bluff because that only seemed to draw more attention to the ranking.

Pat Lile, vice president for community development of the Greater Pine Bluff Chamber of Commerce, said the ratings are just ''the sizzle that sells the book.''

''How can you compare Pine Bluff, with a 63,000 population, with a city of New York's size? It's like comparing apples and oranges,'' Mrs. Robinson said.