BACKGROUND: The potential impact of microwave radiofrequency electromagnetic fields (RF-EMF) emitted by wireless communication devices on neurocognitive functions of adolescents is controversial. In a previous analysis, we found changes in figural memory scores associated with a higher cumulative RF-EMF brain dose in adolescents. OBJECTIVE: We aimed to follow-up our previous results using a new study population, dose estimation, and approach to controlling for confounding from media usage itself. METHODS: RF-EMF brain dose for each participant was modeled. Multivariable linear regression models were fitted on verbal and figural memory score changes over 1 y and on estimated cumulative brain dose and RF-EMF related and unrelated media usage (n = 669-676). Because of the hemispheric lateralization of memory, we conducted a laterality analysis for phone call car preference. To control for the confounding of media use behaviors, a stratified analysis for different media usage groups was also conducted. RESULTS: We found decreased figural memory scores in association with an interquartile range (IQR) increase in estimated cumulative RF-EMF brain dose scores: 0.22 (95% CI: 0.47, 0.03; IQR: 953 mJ/kg per day) in the whole sample, 0.39 (95% CI: 0.67, 0.10; IQR: 953 mJ/kg per day) in right-side users (n = 532), and 0.26 (95% CI: 0.42, 0.10; IQR: 341 mJ/kg per day) when recorded network operator data were used for RF-EMF dose estimation = 274). Media usage unrelated to RF-EMF did not show significant associations or consistent patterns, with the exception of consistent (nonsignificant) positive associations between data traffic duration and verbal memory. CONCLUSIONS: Our findings for a cohort of Swiss adolescents require confirmation in other populations but suggest a potential adverse effect of RF-EMF brain close on cognitive functions that involve brain regions mostly exposed during mobile phone use.