Background: Patellofemoral pain syndrome (PFPS) is a challenging clinical problem affecting adults, adolescents, and physically active populations. PFPS impacts the patient’s trunk kinematics in the frontal plane. Previous studies have found gender-based biomechanical differences in patients with PFPS; however, sagittal trunk kinematics during mini-squats and lumbar proprioception in PFPS have not been studied previously. Objectives: To investigate sagittal trunk excursion (It is defined as the sagittal trunk flexion angle from the start to the end of the mini squat) during mini-squats as well as lumbar repositioning error between individuals with and without PFPS, and determine gender differences in the outcome variables. Methods: A sample of 56 participants aged 18–25 years was enrolled; 30 with PFPS (13 males, 17 females) and 26 asymptomatic controls (11 males, 15 females). The sagittal trunk excursion during mini-squats was examined by two-dimensional (2D) photographic analysis using Surgimap software. Active lumbar flexion repositioning error was assessed using an isokinetic dynamometer. Results: For sagittal trunk excursion, no significant main effect of group was observed ([Formula: see text]). On the other hand, the main effect was significant for gender ([Formula: see text]), as was the interaction effect. Compared to the control group, the PFPS group showed significantly ([Formula: see text]) lower sagittal trunk excursion in females than in males during mini-squats. For active lumbar flexion repositioning error, no evidence was found for significant main or interaction effects ([Formula: see text]). Conclusion: Females with PFPS exhibit a more erect sagittal trunk posture than males during mini-squats. Trunk posture should be considered during weight-bearing activities in PFPS, and gender-specific assessment protocols should be developed.