BackgroundAdolescent girls’ risk of school dropout and reproductive health (RH) challenges may be exacerbated by girls’ attitudes toward their bodies and inability to manage their menstruation. We assessed effects of sanitary pad distribution and RH education on girls in primary grade 7 in Kilifi, Kenya.MethodsA cluster randomized controlled trial design was used. Eligible clusters were all non-boarding schools in three sub-counties in Kilifi County that had a minimum of 25 girls enrolled in primary grade 7. 140 primary schools, 35 per arm, were randomly assigned to one of four study arms: (1) control; (2) sanitary pad distribution; (3) RH education; or (4) both sanitary pad distribution and RH education. Outcomes were school attendance, school engagement, RH knowledge and attitudes, gender norms, and self-efficacy. For outcomes measured both at baseline and endline, difference-in-differences (DID) models were estimated and for outcomes without baseline data available, analysis of covariance models were used.ResultsThe study enrolled 3489 randomly selected girls in primary grade 7, with a mean age of 14.4 (SD 1.5). Girls in arms 2 and 4 received on average 17.6 out of 20 packets of sanitary pads and girls in arms 3 and 4 participated on average in 21 out of 25 RH sessions. Ninety-four percent of the baseline sample was interviewed at the end of the intervention with no differential attrition by arm. There was no evidence of an effect on primary school attendance on arm 2 (coefficient [coef] 0.37, 95% CI − 0.73, 1.46), arm 3 (coef 0.14, 95% CI − 0.99, 1.26) or arm 4 (coef 0.58, 95% CI − .37, 1.52). There was increased positive RH attitudes for girls in arm 3 (DID coef. 0.63, 95% CI 0.40–0.86) and arm 4 (DID coef. 0.85, 95% CI 0.64, − 1.07). There was also an increase in RH knowledge, gender norms and self-efficacy in arms 3 and 4.ConclusionsThe findings suggest that neither sanitary pad distribution nor RH education, on their own or together, were sufficient to improve primary school attendance. However, as the RH education intervention improved RH outcomes, the evidence suggests that sanitary pad distribution and RH education can be positioned in broader RH programming for girls.Trial registration: ISRCTN, ISRCTN10894523. Registered 22 August 2017—Retrospectively registered, http://www.isrctn.com/ISRCTN10894523