Preschool institutions have the important task of supporting the social, emotional, physical and cognitive development of children. Therefore, special attention should be paid to the quality of preschool institutions. The presence of different criteria for evaluating the quality of preschool institutions depending on the level of development, social, political and other factors in certain countries indicates the importance of determining quality indicators that will give the best results in the appropriate environment. The research was aimed at examining parents' opinions about indicators of private preschool institution quality: cooperation and partnership of parents with educators and professional associates, equipment of preschool institutions, additional programs that children attend during the regular program, and nutrition in preschool institutions. Feedback on the quality of the preschool institution from the point of view of the parents of the private preschool institution enables a better understanding and evaluation of the preschool institutions' own work and action to improve the quality of work in all its segments. One of the main goals of the work was to examine the opinion of parents about the quality of private preschool institutions in the area of the city of Rijeka. For the purposes of the research, an online survey questionnaire on Google form was used, which was distributed to parents of children enrolled in private preschool institutions in the area of the city of Rijeka. The questionnaire was constructed on the basis of relevant literature and previous research on the structural and process quality of preschool institutions and accepted criteria of self-evaluation and external evaluation of the quality of preschool institutions, such as the standardized global measures ECERS-3TM and ITERS-3TM with certain adjustments based on the normative framework and pedagogical standards applicable in the Republic of Croatia. The survey included 116 respondents, of which the largest number were female (72.4%). The obtained data were processed in the IBM SPSS Statistics program with descriptive statistics using analysis of contingency tables, chi-square test, t-test for independent samples with 95% certainty and 5% risk and correlation. With a positive opinion about the established collaborative relationships of educators and professional associates with parents that lead to the establishment of positive partner relationships, as well as a positive opinion about the equipment, additional programs and nutrition in private preschool institutions in the area of the city of Rijeka, the respondents expressed their satisfaction with the service provided and the quality of that service. The correlation of the instruments for assessing the quality of preschool institutions used in the research showed their medium to strong connection, so it can be concluded that the quality of a preschool institution is not possible without the quality of all individual elements. Statistical significance confirms that the selected indicators are an adequate measuring instrument for the quality of preschool institutions. The research also showed that there is still room for quality improvement so that it fully meets the expectations of the parents of children who are enrolled in private pre-school institutions in the area of the city of Rijeka.