SMC involves the administration of a treatment course of sulfadoxine-pyrimethamine plus amodiaquine once a month to children aged 3–59 months during the high risk period each year to prevent malaria. SMC over 4 months of the year was introduced in Guinea in 2015 in 6 prefectures, scaling up to 13 prefectures by 2018. The present survey was conducted at the end of the 2019 transmission season to determine SMC coverage and use of LLINs, following national distribution of LLINs in 2019. During the survey, the feasibility of using SMC registers to validate caregiver report of SMC treatments, was investigated. Of children eligible for four SMC treatments, 88% had received an SMC card, and 68% had a card available for inspection in the survey. There was 83% agreement between caregiver report of the number of treatments and the number indicated on the record card. In 55 clusters where SMC registers were available, an attempt was made to find entries in the SMC register for the children in the survey who did not have an SMC card, this was possible for 339/580 (58%) children, and for these children there was 79% agreement with the caregivers’ report. Allowing for the fact that most children who did not receive any SMC treatments will not be listed in the register, it appears that a high proportion of children who received SMC but did not have a card at the survey, were located in registers. We recommend that registers be used in futures surveys to cross-check SMC status. Overall, 81% of children received SMC at cycle 1, 79% at cycle 2, 78% at cycle 3 and 49% at cycle 4. In 97% of treated children, the first dose was directly observed (administered by the CHW, 96.9%, or, in a small number, by the caregiver in the presence of the CHW, 0.4%). A small number of children (0.1%) received the first dose from the caregiver later, not observed by the CHW; the reason given was that the child was away at the time the CHW visited. And for 2.6% of children, although the caregiver received the blister pack, the first dose was not administered. Reported adherence to the unsupervised doses of amodiaquine was very high. Of eligible children treated at cycle 4, caregivers reported that 96.1% received all three daily doses. Caregivers were asked if the child swallowed all the medicine, spat out some medicine, or vomitted all the medicine. Most responded the child swallowed the medicine without vomitting. Of those who were treated, a total of 93.9% of children were reported to have received and swallowed the 3 daily doses without vomitting. In a similar survey in 2018, 30.2% of children slept under a net the night before the survey. In this 2019 survey, 86% (95%CI 79%,90%) of children slept under an LLIN the night before the survey. Of 1038 households surveyed, 89.8% had at least one LLIN but only 36.8% had one LLIN for every 2 persons. This compares with 39.7% had at least one LLIN and 13.1% had one LLIN for every 2 persons in the household, in 2018. Access to a LLIN (the percentage of the population who could sleep under a LLIN if there were two people per net) was 25.4% in 2018. This has increased to 68.2% in the current survey. There was a notable dip in bednet use in children 5-14 years of age, 67% slept under an LLIN the night before the survey compared to 85% of 0-4year-olds and 81% of 15-19-year-olds. This is of concern, children who stop receiving SMC at age 5 need to be protected with an effective net, and specific efforts need to be made to ensure high levels of LLIN use in this age group. In some areas where SMC is currently being implemented, more than 4 cycles of SMC are needed to provide protection throughout the high risk period. Given the success of the current programme and high levels of coverage being achieved each month, extensions to SMC should be considered, the most urgent priority is to provide 5 cycles in some of the current areas, and to expand the number of prefectures where SMC is implemented.