The SHARP-RESPOND study aimed to describe the characteristics and health-seeking behaviours of individuals with undiagnosed hypertension in low-income households in the Philippines and identify the factors influencing undiagnosed hypertension. The analysis is based on observations from 516 people with hypertension from low-income households in the Philippines as part of the RESPOND study. A survey collected the characteristics of participants with undiagnosed hypertension, which were compared to those with diagnosed hypertension to identify determinants of undiagnosed cases. A follow-up survey one year later gathered data on whether undiagnosed participants had subsequently received a formal diagnosis.