ObjectiveIdeal cardiovascular health (CVH) was developed to promote CVH as a key component of primordial prevention. Mobile short message service (SMS) is useful for improving health behaviours. We aim to test the effectiveness of SMS intervention in women to improve CVH.MethodsIn a single-blinded, randomised, controlled study, 620 women, aged 35–70 years, without cardiovascular disease, were enrolled in SMS intervention versus no SMS. CVH metrics by self-report, and biochemical laboratory, anthropometric and blood pressure measurements were collected during home visits at baseline and 9 months. Women were categorised as having poor (0–2), intermediate (3–4) or ideal (5–7) CVH according to the number of ideal CVH metrics. Participants were randomised 1:1 to SMS intervention versus control. SMS was sent every 5–6 days for 9 months. The primary outcome was the difference in the proportion of women with ideal CVH between SMS and control groups at 9 months. Rates of intermediate CVH, poor CVH and each of the seven ideal CV health metrics at 9 months were key secondary endpoints.ResultsAt 9 months, there was no significant difference between groups for the primary outcome (16.3% at baseline and 13.3% at 9 months, and 10.1% and 11.1%, in SMS and control groups, respectively, adjusted RR 1.0; 95% CI 0.6 to 1.6). Similarly, there were no significant differences between groups for the key secondary endpoints. SMS had an acceptance rate of 94.9%.ConclusionsBehavioural SMS intervention did not improve rates of ideal CVH in women, despite being feasible and well received.Trial registration number6377.