This study is a semi-experimental clinical trial to determine the effect of Snoezelen room on pain intensity caused by lumbar puncture in children with acute lymphoblastic leukemia. The study samples include 47 children with acute lymphoblastic leukemia admitted to Ali-Asghar Children’s Hospital and Children's Medical Center which are selected according to the inclusion criteria (age of 4 to 12 years, undergoing lumbar puncture (LP) or intrathecal chemotherapy (IT), lack of mental disability, lack of use of local anesthesia) and the exclusion criteria (use of narcotic, analgesics, tranquillizers during the procedure) and by an easy or available sampling method and divided into two groups of 74 patients of control and test. In the test group, (LP) or (IT) is done at Snoezelen room for 15 to 30 minutes where includes the aquarium, displaying luminous images by the light dancing device on the walls, essential oil burner containing two to five drops of geranium essential oil, 100% playing relaxing music and squeezing the sponge balls to stimulate the sense of touch. After the procedure, according to the child's age and literacy, will be asked him to select and express the rate of his pain intensity numerically or by images. The rate of pain intensity is checked by using the "Scale Pain Oucher" tool. In the control group of the procedure, (IT) (or (LP) is done in typical rooms. The primary outcome of study is reduction in pain intensity of lumbar puncture procedure in children with acute lymphoblastic leukemia