Musculoskeletal physical therapy involves both specific and nonspecific effects. Nonspecific variables associated with the patient, therapist, and setting may influence clinical outcomes. Recent quantitative research has shown that nonspecific factors, including patient-therapist interactions, can influence treatment outcomes. It remains unclear, however, what factors influence patient-therapist interaction. PURPOSE: This qualitative systematic review and meta-synthesis investigated patients' and physical therapists' perceptions of factors that influence patient-therapist interactions. DATA SOURCES: Eleven databases were searched independently. STUDY SELECTION: Qualitative studies examining physical therapists' and patients' perceptions of factors that influence patient-therapist interactions in musculoskeletal settings were included. DATA EXTRACTION: Two reviewers independently selected articles, assessed methodological quality using the Critical Appraisal Skills Programme (CASP), and performed the 3 stages of analysis: extraction of findings, grouping of findings (codes), and abstraction of findings. DATA SYNTHESIS: Thirteen studies were included. Four themes were perceived to influence patient-therapist interactions: (1) physical therapist interpersonal and communication skills (ie, presence of skills such as listening, encouragement, confidence, being empathetic and friendly, and nonverbal communication), (2) physical therapist practical skills (ie, physical therapist expertise and level of training, although the ability to provide good education was considered as important only by patients), (3) individualized patient-centered care (ie, individualizing the treatment to the patient and taking patient's opinions into account), and (4) organizational and environmental factors (ie, time and flexibility with care and appointments). LIMITATIONS: Only studies published in English were included. CONCLUSIONS: A mix of interpersonal, clinical, and organizational factors are perceived to influence patient-therapist interactions, although research is needed to identify which of these factors actually influence patient-therapist interactions. Physical therapists' awareness of these factors could enhance patient interactions and treatment outcomes. Mechanisms to best enhance these factors in clinical practice warrant further study. CI - (c) 2016 American Physical Therapy Association.