Background: The shoulder is a complex, multi-joint structure in the human body. It plays a significant role in activities of self-care, work and leisure. Dysfunction and pain in this region can greatly impact a person’s daily life. Within the broad complaint of shoulder pain, rotator cuff disease (RCD) is the most common condition. RCD can cause extensive disruption of physical activity, but also affects mental health and social participation. RCD consists of tendinopathy of one or more of the muscles of the rotator cuff, partial-thickness tears (PTT), or full-thickness tears (FTT) of the rotator cuff tendons. Objective: To determine the effectiveness of low level laser therapy (LLLT) and routine physical therapy (RPT) on pain intensity, shoulder range of motion (ROM), muscle strength, quality of life, functional disability, supraspinatus tendon thickness and tear thickness in patients with partial tear of supraspinatus tendon. Materials and Methods: 72 patients with confirmed diagnosis of partial tear of supraspinatus tendon through musculoskeletal ultrasound (MSKUS) were randomly allocated into two groups by using a computer generated random sequence table with 36 patients in the experimental group (LLLT+RPT) and 36 patients in the control group (RPT alone). Baseline assessment for pain intensity, shoulder ROM, muscle strength, quality of life, functional disability, supraspinatus tendon thickness and tendon tear thickness were recorded using Visual Analogue Scale (VAS), Universal Goniometer (UG), Oxford Scale for Manual Muscle Testing (MMT), EQ-5D, Disability of Arm, Shoulder and Hand (DASH), and MSKUS respectively, before treatment. All the patients received 18 treatment sessions over a period of 6 weeks (3 sessions per week) and 12 further sessions from 6weeks to 12 weeks follow up (2 sessions per week). At the end of six weeks and 12 weeks, all the outcome measures were assessed again. Results: Repeated Measure Analysis of variance (ANOVA) revealed within groups, significant differences in the mean improvement in all outcome measures in experimental group both at 6 and 12 weeks follow-up. Significant differences were also found in control group for the mean improvement in all outcome measures except non-significant in tendon thickness, tear thickness and supraspinatus strength at 6 weeks whereas significant differences were found in control group for the mean improvement in all outcome measures except non-significant in tendon thickness, tear thickness, supraspinatus strength and deltoid strength at 12 weeks follow-up. An independent t-test revealed between two groups, at 6 weeks, significant differences were found for the mean improvement in tendon thickness, VAS, ROM, QOL and DASH except nonsignificant for tear thickness, supraspinatus strength and deltoid strength, whereas, at 12 weeks, significant differences were found in mean improvement for all outcome measures. However, there was more improvement in the experimental group compared to the control group. Conclusion: The findings of the present study revealed that RPT with and without LLLT was equally effective for all outcome measures for both groups except tendon thickness, tear thickness, supraspinatus strength and deltoid strength for control group in patients with partial tear of supraspinatus tendon.