Although both Traditional Thai Massage (TTM) and joint mobilization have been practiced in Thailand to reduce musculoskeletal pain, a comparative study of these in relieving pain is not been found in the literature. The purpose of this study was to examine the immediate effects of TTM versus joint mobilization on substance P and pain perception in patients with non-specific low back pain. Sixtyseven adults with non-specific low back pain were randomly assigned to receive either TTM (35 people) or joint mobilization (32 people). The duration of each treatment was 10 min. The levels of substance P in saliva and a visual analog scale (VAS) were measured before and 5 min after each treatment. Paired t-test was used to compare outcome variables at baseline with outcome measures 5 min after each treatment. An analysis of covariance (ANCOVA) was performed to compare the difference between groups. Both groups showed a decrease in the level of substance P after treatment when compared with levels pre-treatment (73.86±62.31 pg/ml versus 50.43±64.39 pg/ml in TTM and 80.61±85.26 pg/ml versus 56.27±72.77 pg/ml in joint mobilization; p = 0:019 and 0.006; 95%CI: 4.03–42.82 and 7.48–41.19, respectively). Additionally, there was a marked decrease in VAS after treatment in both groups (4.22±1.98 versus 2.45±1.75 in Thai massage and 4.35±1.71 versus 3.39±1.66 in joint mobilization; p = 0:000 and 0.002, 95%CI: 1.12–2.40 and 0.37–1.55, respectively). There was no significant difference in the substance P level after treatment between the two groups. However, the VAS pain score was slightly different between the groups after treatment (0.88; 95% CI: 0.16–1.59; p = 0:017), where the TTM group reported less pain than the joint mobilization group (2.48±0.25 versus 3.36±0.25 VAS, respectively). Both TTM and joint mobilization can relieve pain in patients with non-specific low back pain. However, TTM yields slightly more beneficial effects than joint mobilization.