The theme of The Room is people's inability to protect themselves from harm and insecurity. At the beginning of the play, Rose bustles about making her husband, Bert, breakfast. Her goal, she says, is to "keep the cold out." Speaking to her husband without his answering, she says, "It's very cold out. I can tell you. It's murder." She attempts to fill her husband with warm food to make sure he isn't cold when he leaves the room to go outside. 

While she seems perturbed and rocks herself, she says, "And we're not bothered. And nobody bothers us." She clings to the hope that she can be at peace in her room. However, after her husband leaves to drive his van, a couple named Mr. and Mrs. Sands knock on the door, as they've heard Rose's room is to let. Later in the play, a blind black man enters the room, and Bert comes home and attacks the man. At the end of the play, Rose says that she is no longer able to see. It is apparent that Roses's attempts to keep the horror and want of the outside world at bay have been futile. Despite her attempt to stay warm, she finds herself out in the cold and vulnerable. 

The primary theme in Pinter's "The Room" is alienation. The atmosphere is menacing, the players all feel at risk and insecure. Pinter explained the alienation theme in an interview: 

Two people in a room. I am dealing a great deal of the time with this image of two people in a room. The curtain goes up on stage and I see it as a very potent question: What is going on between two people in the room? Is someone going to open the door and come in? ---obviously they are scared of what is outside the room. Outside the room there is a world bearing upon them which is frightening. I am sure it is frightening to you and me as well."

The tension is intensified by the juxtaposition of security vs. insecurity. The room itself is safe and secure; but outside, the unknown lurks, a void to be feared. The occupants are unaware of some very basic information that makes them wary of what lies beyond the seemingly-solid walls. For example, they do not know what floor the room is on and or even how many floors are in the house. They are alienated completely from everything beyond the room.