Background: Prostaglandin analogues (PGAs) reduce intraocular pressure (IOP) in patients with primary open-angle glaucoma (POAG); however, these medications may affect the ocular surface and elicit ocular discomfort when preserved with benzalkonium chloride (BAK). Hence the above study was taken to evaluate the benefit of BAK-free formulations of travoprost. The objectives of the study were to compare the efficacy, safety of topical BAK-free travoprost 0.004% versus BAK-preserved travoprost 0.004% in patients with primary open angle glaucoma.Methods: 40 patients with POAG who fulfilled the inclusion /exclusion criteria were randomised into two groups of 20 each to receive BAK-free travoprost 0.004% or BAK-preserved travoprost once daily in the evening. Efficacy was measured in terms of reduction in IOP monitored at 4, 8 and 12 weeks from baseline. Ocular surface disease index (OSDI) questionnaire was used to assess the ocular surface symptoms. Safety was assessed by monitoring treatment emergent adverse drug reactions (ADRs).Results: Both the study medications were effective in reducing IOP when compared to baseline. Mean IOP reduction from baseline to week 12 was 11±3mmHg (p <0.001), 10.78±3.01mmHg, (p<0.001) in BAK-free travoprost and BAK-preserved travoprost groups respectively. Both produced equivalent reductions in IOP at the end of 4 (7.89±1.82 vs 7.63±2.83, p=0.72), 8 (9.94±2.75 vs10.05±2.75, p=0.90), and 12 weeks (11±3 vs10.78±3.01, p=0.82). BAK-free travoprost demonstrated significantly lower OSDI scores (15.10±3.60) compared to BAK- preserved travoprost (23.47±7.10) at 12 weeks (p <0.0001). There was no significant difference in occurrence of conjunctival hyperaemia between the study drugs (c2 = 0, df = 1, p = 1) and BAK-free travoprost was well tolerated.Conclusions: BAK-free and BAK-preserved travoprost significantly reduced IOP at 12 weeks. But, BAK- free travoprost produced significantly less ocular surface symptoms as compared to BAK- preserved travoprost. Hence it could be a favourable option in POAG patients with ocular surface disease symptoms.