According to Helen’s Fisher theory of temperament which is based on a biological basis there are four dimensions of temperament: curious/energetic, cautious/social norm compliant, analytical/tough-minded, prosocial/empathetic. Aim of this research was to test the relation of Fisher’s temperament dimensions and some sociodemographic and relationship features on a sample of young adult participants. Also, aim was to test interrelationship of four temperament dimensions with couples in romantic relationships. The sample consisted of 864 participants who were in the age range from 18 to 40 years of which 276 couples. Participants filled out online Fisher’s Temperament Inventory and sociodemographic data were collected. It was found that men compared to women were more analytical/tough-minded, while women compared to men were more prosocial/empathetic. Members of a particular religion in relation to those who were not, were more cautious/social norm compliant. More conservative individuals compared to the more liberal were more cautious/social norm compliant and less prosocial/empathetic. Individuals who had a more expressive opinion about sex as an essential part of successful relationship compared to those who had a less expressive opinion about that were more curious/energetic and analytical/tough-minded and less cautious/social norm compliant. The more educated individuals compared to the less educated did not differ on the dimension of temperament curious/energetic. In a sample of women and men who were in a romantic relationship it was found that expression of curiosity and energy as well as of caution and social norm compliance in women positively associated with expression of curiosity and energy as well as of caution and social norm compliance in men. Expression of analyticity and tough mindedness in women is positively associated with expression of prosociality and empathy in men and vice versa. In couples sample was found agreement in age, the level of religiosity, the level of education, political orientation and the importance of sex as an essential part of a successful relationship.