The extensively used phototherapy for neonatal jaundice has been widely discussed 1,2 , and its success presumably depends at least in part on the photodegradation of bilirubin IXa (1) to excretable, water-soluble products. McDonagh has shown that bilirubin is a singlet oxygen (lo ) sensitizer3 2 , and Bonnett and Stewart have recently reinforced this beliep. Some of the water soluble mono-and dipyrroles from in vitro photooxidation of 1 have been identi-fiedS'6'7 . OstrowB'g'10 and S&mid" have also indicated that the in vitro photo-destruction -of ,J, gives biliverdin (a), and Ostrow' has postulated that & is an intermediate in the photooxiption of J,. In our work on the photooxidation of ,J we have identified & as a photoproduct , but we do not believe that & is the precuri$r to photoproducts of 1, for Q is photodestroyed at a considerab;: slower rate than is ,$ . Furthermore, McDonagh has shown that 5 is a singlet oxygen quencher . Despite these findings, very little is know of the photo- oxidation products of Q14. We wish to report here on the first isolation and structure proof of hematinic acid methyl ester (2) and of a methanol propentdyopent adduct ($ from photooxidation of biliverdin dimethyl ester (&). Crude biliverdin IXa (a) was prepared in 90% yield by controlled oxidation of bilirubin IXa (,J,) [lo0 mg, Ratheson, Coleman and Bell] using benzoquinone (101 mg) in 50 ml ;: dimethylsulfoxide-acetic acid (9:1 v/v) according to the procedure of Bonnett and McDonagh . The Pure dimethyl ester (a) was prepared from 2 (22% overall yield from 1) by esterification using BF3-methano115 followed by preparative thin layer chromatography (Silica Gel F, M. Woelm,