Eugene O’Neill is the father of modern American drama. His masterpiece Long Day’s Journey into Night is one of the most famous plays in English literature. It is a play about a twentieth-century family and the grueling realities it had to face. It is a semi-autobiographical play that concerns with the Tyrone family. There are four main characters in the play. The father and the mother and their two sons Jamie and Edmund. Apparently, the family seems to be a happy one but the harsh reality is that they are bind to each other not only by hope and love but also by guilt, anger, and their pasts. The story deals with the mother’s addiction to morphine, the father’s covetousness, the older brother’s self-indulgence, and the younger brother’s illness with tuberculosis. To depict the lack of communication among the family members, their isolation and attempt to hide the reality from each other and themselves, O’Neill uses fog as a metaphor. Fog illustrates obscurity, confusion, and frustration. The setting of the play is seaside Connecticut in Tyrone’s summerhouse, Monte Christo cottage, near a harbor. The fog is used to set the scene since the house is located near a harbor. But more important is the use of fog to symbolize the condition of the family and at the same time to parallel the family’s attempt to obscure reality. As the fog descends around Tyrone’s summer home another fog falls on the family within. The atmospheric changing conditions of the play correspond to the family’s change of attitude, from one of hope to one of despair. The fog is used also by O’Neill not only to symbolize a way to escape reality but to symbolize the inability of a man to see beyond what is apparently real.