This study is a single-blind, randomized clinical trial. This study is performed to determine the effect of aromatherapy massage with lavender oil on pain, stiffness and physical function in patients with osteoarthritis of the knee. Inclusion Criteria are those: Approved osteoarthritis knee by Rheumatologist; having knee joint pain that scored 4 cm or above on a 10 cm visual analog scale in the past 3 months; persons who are able to understand explanations and complete the interview; no having cancer, pregnancy and blood clotting disorders such as hemophilia. Participants which have knee surgery during the study, prescription physiotherapy for the knee joint pain during the study, an allergic reaction towards lavender essential oil during the study and the lack of willingness to continue participation in the study, will be excluded. 90 patients osteoarthritis of the knee who have the inclusion criteria of the study are selected by convenient sampling method and are randomly divided into three groups. An experimental group (N= 30) who receives a session of twenty minutes of effleurage massage with 5 cc of 3% lavender essential oil on both lower limbs nine times within 3 weeks, a placebo group (N= 30) who receives a session of twenty minutes of effleurage massage with 5 cc of almond oil on both lower limbs nine times within 3 weeks, and control group (N= 30) who receives no massage. In this study, Lavender essence and almond oil are provided by the Barij Essence Pharmaceudical Company (Kashan, Iran). Assessment is done at baseline, immediately after the intervention, post 1-week and post 4 weeks after treatment. Changes from baseline to the end of treatment are assessed on knee pain intensity, stiffness level and physical functioning by WOMAC (Western Ontario and McMaster Universities Osteoarthritis index) and VAS (Visual Analogue Scale).In this study, those who are going to fill out the questionnaire are not aware of any experiments on each of participants.