Objective:To compare the effects of conventional treatment alone and combined with quadratus lumborum(QL) dry needling on maximal isometric force of the gluteus medius(GM), knee pain and function in patients with patellofemoral pain syndrom(PFPS). Methods:Participants with PFPS(N=56) were randomly assigned to intervention and control groups. Both groups received conventional physiotherapy for 6 sessions. Besides the above intervention, the intervention group received also QL dry needling for 3 sessions. Pain (Visual analog scale), function (Kujala score) and maximal isometric force of GM were recorded at baseline, immediately after the first and sixth session. Analysis of variance(2groups*3times) was used to compare within- and between-group differences. Results:At baseline, no variable showed significant differences between groups (P>0.05). The six-session treatment led to a significant reduction in pain intensity and function and improvement of maximal isometric force of GM in both groups compared to baseline and immediately after the first session (p <0.05). There were no significant differences in all variables between two groups after six sessions. Conclusions:The current clinical trial suggests that QL dry needling did not result in improved outcomes for maximal isometric force of the GM, knee pain and function in individuals with PFPS. What is already known about this topic? Gluteus medius dysfunction may cause patellofemoral pain syndrome. In response to dysfunction of Gluteus medius, Quadratus lumborum , which is the synergy of this muscle, is prone to become overuse. muscle overuse can lead to the development of trigger points. Subjects with patellofemoral pain syndrome have a higher prevalence of trigger points in Quadratus lumborum causing inhibition of Gluteus medius. What does this article add? the effects of Quadratus lumborum dry needling were investigated among people with patellofemoral pain syndrome. maximal isometric force of the Gluteus medius, knee pain and function were assessed to evaluate the impact of Quadratus lumborum dry needling.