Celibacy is a condition that deprives human beings from some social and interactive opportunities due to lack of married life, and can provoke loneliness and social isolation. In this regard, this study will follow two goals: how much single girls over 30 in Yazd suffer from social isolation and what factors create and exacerbate this isolation? This is a survey study with statistical population of 2613 which 139 girls were selected among them as the sample population through snowball sampling method. The results indicated that the average rate of social isolation among the sample population was 63.09% and this represented a relatively high degree of isolation. From among the remaining variables in the regression model, traditional beliefs and perceptions of oneself have the greatest impact on social isolation. The greatest impact belongs to ones' perception of herself. 29.8% of the variance of social isolation can be explained by the linear combination variance of independent variables.