This 1958 Pinter play -- at the time marked ''Discarded'' by its author -- was finally produced two years ago in London and has come to New York via the Trinity Square Repertory Company of Providence. It combines the surreal qualities of a Kafka nightmare and a Marx Brothers farce. Some of it is very funny, and not a little of it is horrifying. All of it is adeptly acted in this production at the Playhouse Theater, staged by Adrian Hall.
The grotesquely realistic fantasy takes place in a mental institution referred to by its onerous staff members as a ''rest home.'' The patients (or inmates) never appear and are referred to only by numbers. Their plight is obvious from the unfeeling attitudes evidenced by ex-Colonel Roote, the bureaucrat in charge, and his subordinates. Offstage incidents include the death of one patient, the giving birth by another, and a murderous finale of Grand Guignol proportions.
''The Hothouse'' is at its most genuinely comic in the Pinterian version of bureaucracy at work - particularly in the exchanges between the blitheringly Blimpish Roote (George Martin) and Gibbs (Richard Kavanaugh), the suavely impudent second-in-command who can't wait for the order of natural succession to take its course.
The wild but not so improbable plot also involves the soberly tailored, promiscuous Miss Cutts (Amy Van Nostrand); the toadying Lush (Peter Gerety); understaffman Tubb (Howard London); and Lamb (Dan Butler), a naive eager-beaver.
The bizarre horror comedy ends when Gibbs gives his bureaucrat's report to the London ministry official (David C. Jones) under which the institution operates.
In any age and clime, the Establishment is fair game for 40 whacks, with or without slapsticks. The attacks by Pinter, gifted word man that he is, are verbal as well as physical. Yet while ''The Hothouse'' contains a minimum of its author's characteristic ambiguities, it also lacks the humanity of plays like ''The Caretaker,'' which was written at about the same time. The only sympathetic characters at this institution are the unfortunate unseen patients, who are undoubtedly meant to serve the Pinter attack on official indifference. This doesn't alter the fact that the characters who carry the story are a totally unsympathetic lot.
The ingenuity and theatricalism of the production receive a spectacular assist from Eugene Lee's arrangement of institutional clutter, networks of hallways and stairways, and the chain-link partition behind which the senior staff incarcerates itself. Mr. Lee adds an environmental effect by extending two ranks of merciless institutional lights into the auditorium. The production has been appropriately costumed by William Lane.