Purpose: the transformation of marriage patterns and family formation by following transition from traditional society to a modern society causes changes in goals, function of family formation. The aim of this study was comparative investigation of the attitudes of single and married individuals about marriage function. Materials and method: the study performed by qualitative method. The statistical society included all married and single men and women in Tehran city. Sample size was 55 single and 57 married men. 66 single and 60 married women.  They were selected using purposeful and available sampling method. First, the statistical analysis performed through content analysis of the subject’s response to an open question as "What is the function of marriage” and after categorizing the responses by several psychologists, using the chi-square test was evaluated agreement between comments of married and single people. Findings: the response of subjects classified in six categories of physiological (physical), psychological, social, economic, religious and spiritual functions and comparison of groups showed significant differences in these categories. There was consistent between single and married people's comments about physiological function of marriage. Disagreement seen with regard to psychological, social and economic function. The married groups more than the single groups had investigated spiritual and religious category. Discussion: despite consistent and discrepancies resulting from the change in people's views about marriage function; as individuals consider functions and benefits for marriage, indicating the place and value of marriage in today's society and  in consultations.