Background: Rheumatic diseases in children are associated with significant morbidity and poor health-related quality of life (HRQOL). There is no health-related quality of life (HRQOL) scale available specifically for children with less common rheumatic diseases. These diseases share several features with systemic lupus erythematosus (SLE) such as their chronic episodic nature, multi-systemic involvement, and the need for immunosuppressive medications. HRQOL scale developed for pediatric SLE will likely be applicable to children with systemic inflammatory diseases.Findings: We adapted Simple Measure of Impact of Lupus Erythematosus in Youngsters (SMILEY (c)) to Simple Measure of Impact of Illness in Youngsters (SMILY (c)-Illness) and had it reviewed by pediatric rheumatologists for its appropriateness and cultural suitability. We tested SMILY (c)-Illness in patients with inflammatory rheumatic diseases and then translated it into 28 languages. Nineteen children (79% female, n= 15) and 17 parents participated. The mean age was 12 +/- 4 years, with median disease duration of 21 months (1-172 months). We translated SMILY (c)-Illness into the following 28 languages: Danish, Dutch, French (France), English (UK), German (Germany), German (Austria), German (Switzerland), Hebrew, Italian, Portuguese (Brazil), Slovene, Spanish (USA and Puerto Rico), Spanish (Spain), Spanish (Argentina), Spanish (Mexico), Spanish (Venezuela), Turkish, Afrikaans, Arabic (Saudi Arabia), Arabic (Egypt), Czech, Greek, Hindi, Hungarian, Japanese, Romanian, Serbian and Xhosa.Conclusion: SMILY (c)-Illness is a brief, easy to administer and score HRQOL scale for children with systemic rheumatic diseases. It is suitable for use across different age groups and literacy levels. SMILY (c)-Illness with its available translations may be used as useful adjuncts to clinical practice and research.Rutgers State Univ, Robert Wood Johnson Med Sch, New Brunswick, NJ 08903 USARutgers State Univ, Child Hlth Inst New Jersey, New Brunswick, NJ 08901 USAHosp Special Surg, New York, NY 10021 USAUniv Michigan, Ann Arbor, MI 48109 USARed Cross War Mem Childrens Hosp, Cape Town, South AfricaAin Shams Univ, Pediat Allergy Immunol & Rheumatol Unit, Cairo, EgyptAin Shams Univ, Pediat Rheumatol Pediat Allergy Immunol & Rheum, Cairo, EgyptKing Faisal Specialist Hosp & Res Ctr, Riyadh 11211, Saudi ArabiaCharles Univ Prague, Prague, Czech RepublicGen Univ Hosp, Prague, Czech RepublicUniv Hosp Motol, Dept Pediat, Prague, Czech RepublicAarhus Univ, Hosp Skejby, Aarhus, DenmarkRigshosp, Juliane Marie Ctr, DK-2100 Copenhagen, DenmarkUniv Med Ctr, Dept Pediat Immunol, Utrecht, NetherlandsWilhelmina Childrens Hosp, Utrecht, NetherlandsGreat Ormond St Hosp Sick Children, Children NHS Fdn Trust, Renal Unit, London, EnglandLyon Univ, Hosp Civils Lyon, Rheumatol & Dermatol Dept, Lyon, FranceMed Univ Innsbruck, A-6020 Innsbruck, AustriaPrim Univ Doz, Bregenz, AustriaHamburg Ctr Pediat & Adolescence Rheumatol, Hamburg, GermanyAsklepios Clin Sankt, Augustin, GermanyUniv Zurich, Childrens Hosp, Zurich, SwitzerlandAristotle Univ Thessaloniki, Pediat Immunol & Rheumatol Referral Ctr, GR-54006 Thessaloniki, GreeceIsrael Meir Hosp, Kefar Sava, IsraelSanjay Gandhi Postgrad Inst Med Sci, Lucknow, Uttar Pradesh, IndiaSemmelweis Univ, H-1085 Budapest, HungaryAnna Meyer Hosp, Florence, ItalyUniv Siena, Res Ctr System Autoimmune & Autoinflammatory Dis, I-53100 Siena, ItalyUniv Florence, Florence, ItalyOsped Pediat Bambino Gesu, IRCCS, Pediat Rheumatol Unit, Rome, ItalyUniv Genoa Pediat II Reumatol, Ist G Gaslini EULAR, Ctr Excellence Rheumatol, Genoa, ItalyUniv Cattolica Sacro Cuore, Inst Pediat, Rome, ItalyUniv Padua, Dept Pediat, Pediat Rheumatol Unit, Padua, ItalyYokohama City Univ, Sch Med, Yokohama, Kanagawa 232, JapanUniv Estadual Paulista, UNESP, Botucatu, SP, BrazilUniv Fed Sao Paulo, Dept Pediat, Sao Paulo, BrazilUniv Estadual Campinas, Dept Med, Campinas, SP, BrazilUniv Fed Rio de Janeiro, Dept Pediat, Rio De Janeiro, BrazilUniv Estado do, Adolescent Hlth Care Unit, Div Pediat Rheumatol, Rio De Janeiro, BrazilUniv Sao Paulo, Fac Med, Childrens Inst, Dept Pediat,Pediat Rheumatol Unit, Sao Paulo, BrazilChildrens Inst, Pediat Rheumatol Unit, Sao Paulo, BrazilClin Pediat I, Cluj Napoca, RomaniaInst Rheumatol, Belgrade, SerbiaUniv Childrens Hosp, Univ Med Ctr Ljubljana, Ljubljana, SloveniaHead Rheumatol Hosp Pedro Elizalde, Buenos Aires, DF, ArgentinaHosp Gen Mexico City, Mexico City, DF, MexicoHosp Infantil Mexico Fed Gomez, Mexico City, DF, MexicoHosp San Juan Dios, Barcelona, SpainHosp Univ Valle Hebron, Barcelona, SpainMt Sinai Med Ctr, New York, NY 10029 USAMt Sinai Med Ctr, Miami Beach, FL 33140 USAComplejo Hosp Univ Ruiz & Paez, Bolivar, VenezuelaHacettepe Univ, Dept Pediat, Ankara, TurkeyIstanbul Univ, Cerrahpasa Med Sch, Istanbul, TurkeyFMF Arthrit Vasculitis & Orphan Dis Res Ctr, Inst Hlth Sci, Ankara, TurkeyUniv Calgary, Dept Pediat, Alberta Childrens Hosp, Res Inst, Calgary, AB T2N 1N4, CanadaUniv Estadual Paulista, UNESP, Botucatu, SP, Brazil