Sexual needs are among the primary needs of humans to be fulfilled. The rise of lesbian behavior in Correctional Institution "X" is an interesting phenomenon, as lesbianism is regarded as a deviant behavior, especially with regard to religious values and norms. Correctional Institution "X" also prohibits any form of relations among inmates of different sexes, much less between those of the same sex.The research is qualitative and descriptive, with informants including lesbian inmates, non-lesbian inmates and institutional staff members. In the collection of data, the researcher acted as participant, gathering data with direct observation and in-depth interviews.The theory used in the study is the subculture theory of John Irwin and Donald R. Cressey. A subculture is a group of norms, values and beliefs differing from norms, values and beliefs of the dominant culture. A prison subculture is a group of patterns arising in the prison environment, different from the dominant culture. A subculture is a choice in facing prison life, having opposing norms and values. According to Albert K. Cohen, a subculture appears from a feeling of solidarity in a group having norms suitable to group members' requirements. Cohen explains further that deviant behavior includes actions considered in violation of norms and expectations of the society.The research shows that prison affects sexual behavior of inmates. Lesbian behavior can be regarded as a subculture, noting the rise of values, symbols, and norms. Within correctional institutions, lesbian behavior rises due to lack of legal means to obtain fulfillment of sexual needs. If inmates are provided with a legal means to fulfill their sexual needs, it is possible that lesbian behavior would not arise within correctional institutions.