The [Rh-2(OAc)(4)] catalyzed decomposition of (N-(p-nitrobenzenesulfonyl)imino)phenyliodinane (PhI=NNs) in the presence of olefins affords aziridines In yields of 18-85%. The aziridination of cis-beta-methylstyrene (1h) and cis-hex-2-ene (1k) is stereospecific. However, with cis-stilbene (Im) a ca 3:1 mixture of cis- and trans aziridines 2m and 2l is obtained. With chiral catalysts asymmetric inductions in up to 73% ee are obtained.