Background: Physical inactivity is a significant cause of premature deaths globally, yet many physiotherapists)PT's) have little knowledge of the World Health Organization's physical activity guidelines (PA). Objectives: To assess the knowledge of Israeli PT's regarding the World Health Organization's (WHO) recommendations for PA for adults and adolescents. Secondary aims were to determine how many Israeli PT's, are recommending PA for their patients and to evaluate the knowledge level of Israeli PT's in relation to PT's in other countries. Design: Cross-sectional online survey. Participants: Of the 1413 Israeli PT's offered the survey, 1062 (75%) completed it, which represents 16.4% of the 6450 licensed PT's in Israel. Results: A mere 6.8% physiotherapists were aware of the WHO-recommended level of adult PA, and only 4% were knowledgeable of the recommendations for adolescents. Novice PT's (5 > years of experience) knew significantly more about adult PA recommendations (P < 0.05) than did the more senior physiotherapists. Nine out of every ten (90%) PT's routinely initiate conversations about PA, 83.5% signpost to PA support elsewhere, and 70.5% deliver brief intervention themselves for PA. The main barriers to promoting PA were (1) the belief that promotion would not change patient behavior, (2) lack of time, and (3) perceived lack of skills at counseling for behavior change. Conclusions: Israeli PT's have poor knowledge of the WHO's adults and adolescent guidelines for PA. Lack of knowledge among PT's regarding the WHO's PA guidelines is a recurrent global problem that requires immediate attention.