A cohort of 9 23 mo nths old Addis Ababa children were assessed as to their immune response to meas l es vaccine in relation to their nutriti o nal status. Of the 307 pairs of blood spec imens analyzed for meas les antibody, 207 ( 67.4 %) (32.6%) had had a negati ve preva c einiltion tit er while 10 0 prevaccination titers th a t we r e s e rop os iti~ e. Am 0 n g the s e ron ega t i ve s a 95% s e ro c 0 n "e r s ion rat e was obtained with no difference b et"r>en the malnourished and well n o urish e d. Ther!' Has n o differen ce in side e ffe cts repo rt e d to th e meas l es vaccin e betwe!'n well n ou ri shed and maln o urished c hildr e n. raccination of thos e wh o were seropositive at th e outset didn't r esults in an), booster e f f e c t, de fin e d by a f 0 u r f 0 I d r i s e fr o m the pre \- i 0 U s tite r'. Only 9 (9%) o f these ch ildr e n showed a booster effect. A va lidity test f or his to r y of measles aga inst the laboratory results gave a 9 5. 1% specificity and 3 1% sensitivity rat e . A secon <! gro"p of c hildr e n "ho were under 9 mo n t h s and we re not EP[ eligih l e we r e also analyzed as to their antibody status Out of 95 r llil d r en wi t h a n a lr zab l e samples 47 (4 9 . 5% ) h a d de tect"blp mat erna l antibod;' whil e 48 (50.5%) had n o detectable mate rn a l antibodies. The l'Bning sets in at an earl,' age a nd r eac hes 100% by 6 - 8 mo nth s of age. x