Aim: To compare the efficacy & safety of blue light vs topical application of 1% clindamycin solution in the treatment of mild to moderate inflammatory acne vulgaris. Study Design: Comparative interventional study done in Dermatology Outpatient Department Unit-II, KEMU/ Mayo Hospital, Lahore six months i.e. 1-06-2014 – 30-11-2014 Methodology: After an informed and written consent, 130 patients fulfilling the selection criteria were enrolled in the study and divided in two study groups A & B by balloting method. At first visit, a detailed history and clinical examination was recorded on a specially designed proforma. The acne was graded according to the acne grading scale of American Academy of Dermatology.4,13 Group A was exposed to blue light for twenty minutes twice weekly for eight weeks. Group B was given 1% clindamycin to apply twice daily for a period of eight weeks. Post- treatment follow up was done for next four weeks. Patients were assessed at 2nd, 4th, 6th, 8th, 10th, and 12th week. All findings and side effects were recorded on a predesigned proforma. To determine the efficacy of treatment, Acne Severity Index (ASI) was used.5 Result: Efficacy of treatment [≥ 50% improvement in ASI score] was seen in 39(60%) patients in blue light group while in clindamycin group it was achieved in 8 (12.3%) patients only. Blue light group had significantly less number of side effects observed in 35 (37.23%) patients while clindamycin group had a higher number of side effects observed in 59 (62.77%) patients, p-value= 0.013. Conclusion: Blue light is more efficacious and safer than topical 1% clindamycin in the treatment of mild to moderate inflammatory acne vulgaris. Keywords: Blue light, 1% Clindamycin, Acne vulgaris