Background: Renal and liver transplantation influences the quality of life of the patients who undergo these procedures. Therefore, the aim of the present study was to analyze possible differences in liver and kidney transplantation in relation to the patient’s sex and to determine their impact on quality of life. Methodology: An observational study was carried out with 147 patients with liver (n = 70) and kidney (n = 77) failure on the transplantation waiting list. The possible influence of sex on clinical, sociodemographic, and psychological aspects of the patients’ quality of life before and 6 months after transplantation was analyzed. Questionnaires on health-related quality of life (SF-36), the perception of social and family support (EASP), and coping strategies (CEA), the depression and anxiety scale (HAD), and the Eysenck personality inventory (EPI) were used. A univariate analysis was performed according to sex using statistical tools including the Chi-square test, the t-test, and a univariate linear analysis of variance. Results: In patients on the waiting list for liver transplantation, we found sex differences in terms of age (p = 0.040), time of evolution of end-stage liver disease (p = 0.013), etiology (p = 0.07), and associated complications, as well as in the consumption of tobacco and other psychotropic substances (p = 0.022), while patients on the waiting list for renal transplantation showed sex-related differences in terms of etiology (p = 0.012) and alcohol consumption (p = 0.005). The results showed significant sex-related differences in sociodemographic and psychological aspects, but no significant sex-related differences were observed in global quality of life in either of the two assessments in both groups. Discussion: The findings suggest that improvement in quality of life after liver or kidney transplantation is not influenced by the patient’s sex.